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data-event-name="pinnable-header.vector-toc.pin">move to sidebar</button> <button class="vector-pinnable-header-toggle-button vector-pinnable-header-unpin-button" data-event-name="pinnable-header.vector-toc.unpin">hide</button> </div> <ul class="vector-toc-contents" id="mw-panel-toc-list"> <li id="toc-mw-content-text" class="vector-toc-list-item vector-toc-level-1"> <a href="#" class="vector-toc-link"> <div class="vector-toc-text">(Top)</div> </a> </li> <li id="toc-History" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#History"> <div class="vector-toc-text"> <span class="vector-toc-numb">1</span> <span>History</span> </div> </a> <ul id="toc-History-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Operation" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#Operation"> <div class="vector-toc-text"> <span class="vector-toc-numb">2</span> <span>Operation</span> </div> </a> <ul id="toc-Operation-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Spark_plug_construction" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#Spark_plug_construction"> <div class="vector-toc-text"> <span class="vector-toc-numb">3</span> <span>Spark plug construction</span> </div> </a> <button aria-controls="toc-Spark_plug_construction-sublist" class="cdx-button cdx-button--weight-quiet cdx-button--icon-only vector-toc-toggle"> <span class="vector-icon mw-ui-icon-wikimedia-expand"></span> <span>Toggle Spark plug construction subsection</span> </button> <ul id="toc-Spark_plug_construction-sublist" class="vector-toc-list"> <li id="toc-Parts_of_the_plug" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Parts_of_the_plug"> <div class="vector-toc-text"> <span class="vector-toc-numb">3.1</span> <span>Parts of the plug</span> </div> </a> <ul id="toc-Parts_of_the_plug-sublist" class="vector-toc-list"> <li id="toc-Terminal" class="vector-toc-list-item vector-toc-level-3"> <a class="vector-toc-link" href="#Terminal"> <div class="vector-toc-text"> <span class="vector-toc-numb">3.1.1</span> <span>Terminal</span> </div> </a> <ul id="toc-Terminal-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Insulator" class="vector-toc-list-item vector-toc-level-3"> <a class="vector-toc-link" href="#Insulator"> <div class="vector-toc-text"> <span class="vector-toc-numb">3.1.2</span> <span>Insulator</span> </div> </a> <ul id="toc-Insulator-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Ribs" class="vector-toc-list-item vector-toc-level-3"> <a class="vector-toc-link" href="#Ribs"> <div class="vector-toc-text"> <span class="vector-toc-numb">3.1.3</span> <span>Ribs</span> </div> </a> <ul id="toc-Ribs-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Insulator_tip" class="vector-toc-list-item vector-toc-level-3"> <a class="vector-toc-link" href="#Insulator_tip"> <div class="vector-toc-text"> <span class="vector-toc-numb">3.1.4</span> <span>Insulator tip</span> </div> </a> <ul id="toc-Insulator_tip-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Seals" class="vector-toc-list-item vector-toc-level-3"> <a class="vector-toc-link" href="#Seals"> <div class="vector-toc-text"> <span class="vector-toc-numb">3.1.5</span> <span>Seals</span> </div> </a> <ul id="toc-Seals-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Metal_case/shell" class="vector-toc-list-item vector-toc-level-3"> <a class="vector-toc-link" href="#Metal_case/shell"> <div class="vector-toc-text"> <span class="vector-toc-numb">3.1.6</span> <span>Metal case/shell</span> </div> </a> <ul id="toc-Metal_case/shell-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Central_electrode" class="vector-toc-list-item vector-toc-level-3"> <a class="vector-toc-link" href="#Central_electrode"> <div class="vector-toc-text"> <span class="vector-toc-numb">3.1.7</span> <span>Central electrode</span> </div> </a> <ul id="toc-Central_electrode-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Side_(ground,_earth)_electrode" class="vector-toc-list-item vector-toc-level-3"> <a class="vector-toc-link" href="#Side_(ground,_earth)_electrode"> <div class="vector-toc-text"> <span class="vector-toc-numb">3.1.8</span> <span>Side (ground, earth) electrode</span> </div> </a> <ul id="toc-Side_(ground,_earth)_electrode-sublist" class="vector-toc-list"> </ul> </li> </ul> </li> <li id="toc-Spark_plug_gap" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Spark_plug_gap"> <div class="vector-toc-text"> <span class="vector-toc-numb">3.2</span> <span>Spark plug gap</span> </div> </a> <ul id="toc-Spark_plug_gap-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Variations_on_the_basic_design" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Variations_on_the_basic_design"> <div class="vector-toc-text"> <span class="vector-toc-numb">3.3</span> <span>Variations on the basic design</span> </div> </a> <ul id="toc-Variations_on_the_basic_design-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Surface-discharge_spark_plug" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Surface-discharge_spark_plug"> <div class="vector-toc-text"> <span class="vector-toc-numb">3.4</span> <span>Surface-discharge spark plug</span> </div> </a> <ul id="toc-Surface-discharge_spark_plug-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Sealing_to_the_cylinder_head" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Sealing_to_the_cylinder_head"> <div class="vector-toc-text"> <span class="vector-toc-numb">3.5</span> <span>Sealing to the cylinder head</span> </div> </a> <ul id="toc-Sealing_to_the_cylinder_head-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Tip_protrusion" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Tip_protrusion"> <div class="vector-toc-text"> <span class="vector-toc-numb">3.6</span> <span>Tip protrusion</span> </div> </a> <ul id="toc-Tip_protrusion-sublist" class="vector-toc-list"> </ul> </li> </ul> </li> <li id="toc-Heat_range" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#Heat_range"> <div class="vector-toc-text"> <span class="vector-toc-numb">4</span> <span>Heat range</span> </div> </a> <ul id="toc-Heat_range-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Reading_spark_plugs" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#Reading_spark_plugs"> <div class="vector-toc-text"> <span class="vector-toc-numb">5</span> <span>Reading spark plugs</span> </div> </a> <ul id="toc-Reading_spark_plugs-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Indexing_spark_plugs" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#Indexing_spark_plugs"> <div class="vector-toc-text"> <span class="vector-toc-numb">6</span> <span>Indexing spark plugs</span> </div> </a> <ul id="toc-Indexing_spark_plugs-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-See_also" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#See_also"> <div class="vector-toc-text"> <span class="vector-toc-numb">7</span> <span>See also</span> </div> </a> <ul id="toc-See_also-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-References" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#References"> <div class="vector-toc-text"> <span class="vector-toc-numb">8</span> <span>References</span> </div> </a> <ul id="toc-References-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-External_links" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#External_links"> <div class="vector-toc-text"> <span class="vector-toc-numb">9</span> <span>External links</span> </div> </a> <ul id="toc-External_links-sublist" class="vector-toc-list"> </ul> </li> </ul> </div> </div> </nav> </div> </div> <div class="mw-content-container"> <main id="content" class="mw-body"> <header class="mw-body-header vector-page-titlebar"> <nav aria-label="Contents" class="vector-toc-landmark"> <div id="vector-page-titlebar-toc" class="vector-dropdown vector-page-titlebar-toc vector-button-flush-left" title="Table of Contents" > <input type="checkbox" id="vector-page-titlebar-toc-checkbox" role="button" aria-haspopup="true" data-event-name="ui.dropdown-vector-page-titlebar-toc" class="vector-dropdown-checkbox " aria-label="Toggle the table of contents" > <label id="vector-page-titlebar-toc-label" for="vector-page-titlebar-toc-checkbox" class="vector-dropdown-label cdx-button cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--weight-quiet cdx-button--icon-only " aria-hidden="true" ><span class="vector-icon mw-ui-icon-listBullet mw-ui-icon-wikimedia-listBullet"></span> <span class="vector-dropdown-label-text">Toggle the table of contents</span> </label> <div class="vector-dropdown-content"> <div id="vector-page-titlebar-toc-unpinned-container" class="vector-unpinned-container"> </div> </div> </div> </nav> <h1 id="firstHeading" class="firstHeading mw-first-heading"><span class="mw-page-title-main">Spark plug</span></h1> <div id="p-lang-btn" class="vector-dropdown mw-portlet mw-portlet-lang" > <input type="checkbox" id="p-lang-btn-checkbox" role="button" aria-haspopup="true" data-event-name="ui.dropdown-p-lang-btn" class="vector-dropdown-checkbox mw-interlanguage-selector" aria-label="Go to an article in another language. Available in 55 languages" > <label id="p-lang-btn-label" for="p-lang-btn-checkbox" class="vector-dropdown-label cdx-button cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--weight-quiet cdx-button--action-progressive mw-portlet-lang-heading-55" aria-hidden="true" ><span class="vector-icon mw-ui-icon-language-progressive mw-ui-icon-wikimedia-language-progressive"></span> <span class="vector-dropdown-label-text">55 languages</span> </label> <div class="vector-dropdown-content"> <div class="vector-menu-content"> <ul class="vector-menu-content-list"> <li class="interlanguage-link interwiki-af mw-list-item"><a href="https://af.wikipedia.org/wiki/Vonkprop" title="Vonkprop – Afrikaans" lang="af" hreflang="af" data-title="Vonkprop" data-language-autonym="Afrikaans" data-language-local-name="Afrikaans" class="interlanguage-link-target"><span>Afrikaans</span></a></li><li class="interlanguage-link interwiki-ar mw-list-item"><a href="https://ar.wikipedia.org/wiki/%D8%B4%D9%85%D8%B9%D8%A9_%D8%A7%D8%AD%D8%AA%D8%B1%D8%A7%D9%82" title="شمعة احتراق – Arabic" lang="ar" hreflang="ar" data-title="شمعة احتراق" data-language-autonym="العربية" data-language-local-name="Arabic" class="interlanguage-link-target"><span>العربية</span></a></li><li class="interlanguage-link interwiki-az mw-list-item"><a href="https://az.wikipedia.org/wiki/Al%C4%B1%C5%9Fd%C4%B1rma_%C5%9Famlar%C4%B1" title="Alışdırma şamları – Azerbaijani" lang="az" hreflang="az" data-title="Alışdırma şamları" data-language-autonym="Azərbaycanca" data-language-local-name="Azerbaijani" class="interlanguage-link-target"><span>Azərbaycanca</span></a></li><li class="interlanguage-link interwiki-bg mw-list-item"><a href="https://bg.wikipedia.org/wiki/%D0%97%D0%B0%D0%BF%D0%B0%D0%BB%D0%B8%D1%82%D0%B5%D0%BB%D0%BD%D0%B0_%D1%81%D0%B2%D0%B5%D1%89" title="Запалителна свещ – Bulgarian" lang="bg" hreflang="bg" data-title="Запалителна свещ" data-language-autonym="Български" data-language-local-name="Bulgarian" class="interlanguage-link-target"><span>Български</span></a></li><li class="interlanguage-link interwiki-bs mw-list-item"><a href="https://bs.wikipedia.org/wiki/Svje%C4%87ica" title="Svjećica – Bosnian" lang="bs" hreflang="bs" data-title="Svjećica" data-language-autonym="Bosanski" data-language-local-name="Bosnian" class="interlanguage-link-target"><span>Bosanski</span></a></li><li class="interlanguage-link interwiki-ca mw-list-item"><a href="https://ca.wikipedia.org/wiki/Bugia_d%27encesa" title="Bugia d'encesa – Catalan" lang="ca" hreflang="ca" data-title="Bugia d'encesa" data-language-autonym="Català" data-language-local-name="Catalan" class="interlanguage-link-target"><span>Català</span></a></li><li class="interlanguage-link interwiki-cs mw-list-item"><a href="https://cs.wikipedia.org/wiki/Zapalovac%C3%AD_sv%C3%AD%C4%8Dka" title="Zapalovací svíčka – Czech" lang="cs" hreflang="cs" data-title="Zapalovací svíčka" data-language-autonym="Čeština" data-language-local-name="Czech" class="interlanguage-link-target"><span>Čeština</span></a></li><li class="interlanguage-link interwiki-da mw-list-item"><a href="https://da.wikipedia.org/wiki/T%C3%A6ndr%C3%B8r" title="Tændrør – Danish" lang="da" hreflang="da" data-title="Tændrør" data-language-autonym="Dansk" data-language-local-name="Danish" class="interlanguage-link-target"><span>Dansk</span></a></li><li class="interlanguage-link interwiki-de mw-list-item"><a href="https://de.wikipedia.org/wiki/Z%C3%BCndkerze" title="Zündkerze – German" lang="de" hreflang="de" data-title="Zündkerze" data-language-autonym="Deutsch" data-language-local-name="German" class="interlanguage-link-target"><span>Deutsch</span></a></li><li class="interlanguage-link interwiki-et mw-list-item"><a href="https://et.wikipedia.org/wiki/S%C3%BC%C3%BCtek%C3%BC%C3%BCnal" title="Süüteküünal – Estonian" lang="et" hreflang="et" data-title="Süüteküünal" data-language-autonym="Eesti" data-language-local-name="Estonian" class="interlanguage-link-target"><span>Eesti</span></a></li><li class="interlanguage-link interwiki-el mw-list-item"><a href="https://el.wikipedia.org/wiki/%CE%91%CE%BD%CE%B1%CF%86%CE%BB%CE%B5%CE%BA%CF%84%CE%AE%CF%81%CE%B1%CF%82" title="Αναφλεκτήρας – Greek" lang="el" hreflang="el" data-title="Αναφλεκτήρας" data-language-autonym="Ελληνικά" data-language-local-name="Greek" class="interlanguage-link-target"><span>Ελληνικά</span></a></li><li class="interlanguage-link interwiki-es mw-list-item"><a href="https://es.wikipedia.org/wiki/Buj%C3%ADa" title="Bujía – Spanish" lang="es" hreflang="es" data-title="Bujía" data-language-autonym="Español" data-language-local-name="Spanish" class="interlanguage-link-target"><span>Español</span></a></li><li class="interlanguage-link interwiki-eo mw-list-item"><a href="https://eo.wikipedia.org/wiki/Sparkilo" title="Sparkilo – Esperanto" lang="eo" hreflang="eo" data-title="Sparkilo" data-language-autonym="Esperanto" data-language-local-name="Esperanto" class="interlanguage-link-target"><span>Esperanto</span></a></li><li class="interlanguage-link interwiki-eu mw-list-item"><a href="https://eu.wikipedia.org/wiki/Buxia" title="Buxia – Basque" lang="eu" hreflang="eu" data-title="Buxia" data-language-autonym="Euskara" data-language-local-name="Basque" class="interlanguage-link-target"><span>Euskara</span></a></li><li class="interlanguage-link interwiki-fa mw-list-item"><a href="https://fa.wikipedia.org/wiki/%D8%B4%D9%85%D8%B9_(%D8%AE%D9%88%D8%AF%D8%B1%D9%88)" title="شمع (خودرو) – Persian" lang="fa" hreflang="fa" data-title="شمع (خودرو)" data-language-autonym="فارسی" data-language-local-name="Persian" class="interlanguage-link-target"><span>فارسی</span></a></li><li class="interlanguage-link interwiki-fr badge-Q17437798 badge-goodarticle mw-list-item" title="good article badge"><a href="https://fr.wikipedia.org/wiki/Bougie_d%27allumage" title="Bougie d'allumage – French" lang="fr" hreflang="fr" data-title="Bougie d'allumage" data-language-autonym="Français" data-language-local-name="French" class="interlanguage-link-target"><span>Français</span></a></li><li class="interlanguage-link interwiki-gl mw-list-item"><a href="https://gl.wikipedia.org/wiki/Bux%C3%ADa" title="Buxía – Galician" lang="gl" hreflang="gl" data-title="Buxía" data-language-autonym="Galego" data-language-local-name="Galician" class="interlanguage-link-target"><span>Galego</span></a></li><li class="interlanguage-link interwiki-ko mw-list-item"><a href="https://ko.wikipedia.org/wiki/%EC%A0%90%ED%99%94_%ED%94%8C%EB%9F%AC%EA%B7%B8" title="점화 플러그 – Korean" lang="ko" hreflang="ko" data-title="점화 플러그" data-language-autonym="한국어" data-language-local-name="Korean" class="interlanguage-link-target"><span>한국어</span></a></li><li class="interlanguage-link interwiki-hi mw-list-item"><a href="https://hi.wikipedia.org/wiki/%E0%A4%B8%E0%A5%8D%E0%A4%AA%E0%A4%BE%E0%A4%B0%E0%A5%8D%E0%A4%95_%E0%A4%AA%E0%A5%8D%E0%A4%B2%E0%A4%97" title="स्पार्क प्लग – Hindi" lang="hi" hreflang="hi" data-title="स्पार्क प्लग" data-language-autonym="हिन्दी" data-language-local-name="Hindi" class="interlanguage-link-target"><span>हिन्दी</span></a></li><li class="interlanguage-link interwiki-hr mw-list-item"><a href="https://hr.wikipedia.org/wiki/Svje%C4%87ica" title="Svjećica – Croatian" lang="hr" hreflang="hr" data-title="Svjećica" data-language-autonym="Hrvatski" data-language-local-name="Croatian" class="interlanguage-link-target"><span>Hrvatski</span></a></li><li class="interlanguage-link interwiki-id mw-list-item"><a href="https://id.wikipedia.org/wiki/Busi" title="Busi – Indonesian" lang="id" hreflang="id" data-title="Busi" data-language-autonym="Bahasa Indonesia" data-language-local-name="Indonesian" class="interlanguage-link-target"><span>Bahasa Indonesia</span></a></li><li class="interlanguage-link interwiki-is mw-list-item"><a href="https://is.wikipedia.org/wiki/Kerti_(sprengihreyfill)" title="Kerti (sprengihreyfill) – Icelandic" lang="is" hreflang="is" data-title="Kerti (sprengihreyfill)" data-language-autonym="Íslenska" data-language-local-name="Icelandic" class="interlanguage-link-target"><span>Íslenska</span></a></li><li class="interlanguage-link interwiki-it mw-list-item"><a href="https://it.wikipedia.org/wiki/Candela_di_accensione" title="Candela di accensione – Italian" lang="it" hreflang="it" data-title="Candela di accensione" data-language-autonym="Italiano" data-language-local-name="Italian" class="interlanguage-link-target"><span>Italiano</span></a></li><li class="interlanguage-link interwiki-he mw-list-item"><a href="https://he.wikipedia.org/wiki/%D7%9E%D7%A6%D7%AA" title="מצת – Hebrew" lang="he" hreflang="he" data-title="מצת" data-language-autonym="עברית" data-language-local-name="Hebrew" class="interlanguage-link-target"><span>עברית</span></a></li><li class="interlanguage-link interwiki-jv mw-list-item"><a href="https://jv.wikipedia.org/wiki/Busi" title="Busi – Javanese" lang="jv" hreflang="jv" data-title="Busi" data-language-autonym="Jawa" data-language-local-name="Javanese" class="interlanguage-link-target"><span>Jawa</span></a></li><li class="interlanguage-link interwiki-hu mw-list-item"><a href="https://hu.wikipedia.org/wiki/Gy%C3%BAjt%C3%B3gyertya" title="Gyújtógyertya – Hungarian" lang="hu" hreflang="hu" data-title="Gyújtógyertya" data-language-autonym="Magyar" data-language-local-name="Hungarian" class="interlanguage-link-target"><span>Magyar</span></a></li><li class="interlanguage-link interwiki-mk mw-list-item"><a href="https://mk.wikipedia.org/wiki/%D0%A1%D0%B2%D0%B5%D1%9C%D0%B8%D1%87%D0%BA%D0%B0" title="Свеќичка – Macedonian" lang="mk" hreflang="mk" data-title="Свеќичка" data-language-autonym="Македонски" data-language-local-name="Macedonian" class="interlanguage-link-target"><span>Македонски</span></a></li><li class="interlanguage-link interwiki-ml mw-list-item"><a href="https://ml.wikipedia.org/wiki/%E0%B4%B8%E0%B5%8D%E0%B4%AA%E0%B4%BE%E0%B5%BC%E0%B4%95%E0%B5%8D%E0%B4%95%E0%B5%8D_%E0%B4%AA%E0%B5%8D%E0%B4%B2%E0%B4%97%E0%B5%8D" title="സ്പാർക്ക് പ്ലഗ് – Malayalam" lang="ml" hreflang="ml" data-title="സ്പാർക്ക് പ്ലഗ്" data-language-autonym="മലയാളം" data-language-local-name="Malayalam" class="interlanguage-link-target"><span>മലയാളം</span></a></li><li class="interlanguage-link interwiki-ms mw-list-item"><a href="https://ms.wikipedia.org/wiki/Palam_pencucuh" title="Palam pencucuh – Malay" lang="ms" hreflang="ms" data-title="Palam pencucuh" data-language-autonym="Bahasa Melayu" data-language-local-name="Malay" class="interlanguage-link-target"><span>Bahasa Melayu</span></a></li><li class="interlanguage-link interwiki-min mw-list-item"><a href="https://min.wikipedia.org/wiki/Busi" title="Busi – Minangkabau" lang="min" hreflang="min" data-title="Busi" data-language-autonym="Minangkabau" data-language-local-name="Minangkabau" class="interlanguage-link-target"><span>Minangkabau</span></a></li><li class="interlanguage-link interwiki-my mw-list-item"><a href="https://my.wikipedia.org/wiki/%E1%80%85%E1%80%95%E1%80%AB%E1%80%B7%E1%80%81%E1%80%BA_%E1%80%95%E1%80%9C%E1%80%95%E1%80%BA%E1%80%82%E1%80%BA" title="စပါ့ခ် ပလပ်ဂ် – Burmese" lang="my" hreflang="my" data-title="စပါ့ခ် ပလပ်ဂ်" data-language-autonym="မြန်မာဘာသာ" data-language-local-name="Burmese" class="interlanguage-link-target"><span>မြန်မာဘာသာ</span></a></li><li class="interlanguage-link interwiki-nl mw-list-item"><a href="https://nl.wikipedia.org/wiki/Bougie" title="Bougie – Dutch" lang="nl" hreflang="nl" data-title="Bougie" data-language-autonym="Nederlands" data-language-local-name="Dutch" class="interlanguage-link-target"><span>Nederlands</span></a></li><li class="interlanguage-link interwiki-ja mw-list-item"><a href="https://ja.wikipedia.org/wiki/%E7%82%B9%E7%81%AB%E3%83%97%E3%83%A9%E3%82%B0" title="点火プラグ – Japanese" lang="ja" hreflang="ja" data-title="点火プラグ" data-language-autonym="日本語" data-language-local-name="Japanese" class="interlanguage-link-target"><span>日本語</span></a></li><li class="interlanguage-link interwiki-no mw-list-item"><a href="https://no.wikipedia.org/wiki/Tennplugg" title="Tennplugg – Norwegian Bokmål" lang="nb" hreflang="nb" data-title="Tennplugg" data-language-autonym="Norsk bokmål" data-language-local-name="Norwegian Bokmål" class="interlanguage-link-target"><span>Norsk bokmål</span></a></li><li class="interlanguage-link interwiki-pnb mw-list-item"><a href="https://pnb.wikipedia.org/wiki/%D8%B3%D9%BE%D8%A7%D8%B1%DA%A9_%D9%BE%D9%84%DA%AF" title="سپارک پلگ – Western Punjabi" lang="pnb" hreflang="pnb" data-title="سپارک پلگ" data-language-autonym="پنجابی" data-language-local-name="Western Punjabi" class="interlanguage-link-target"><span>پنجابی</span></a></li><li class="interlanguage-link interwiki-pl mw-list-item"><a href="https://pl.wikipedia.org/wiki/%C5%9Awieca_zap%C5%82onowa" title="Świeca zapłonowa – Polish" lang="pl" hreflang="pl" data-title="Świeca zapłonowa" data-language-autonym="Polski" data-language-local-name="Polish" class="interlanguage-link-target"><span>Polski</span></a></li><li class="interlanguage-link interwiki-pt mw-list-item"><a href="https://pt.wikipedia.org/wiki/Vela_de_igni%C3%A7%C3%A3o" title="Vela de ignição – Portuguese" lang="pt" hreflang="pt" data-title="Vela de ignição" data-language-autonym="Português" data-language-local-name="Portuguese" class="interlanguage-link-target"><span>Português</span></a></li><li class="interlanguage-link interwiki-ro mw-list-item"><a href="https://ro.wikipedia.org/wiki/Bujie" title="Bujie – Romanian" lang="ro" hreflang="ro" data-title="Bujie" data-language-autonym="Română" data-language-local-name="Romanian" class="interlanguage-link-target"><span>Română</span></a></li><li class="interlanguage-link interwiki-ru mw-list-item"><a href="https://ru.wikipedia.org/wiki/%D0%A1%D0%B2%D0%B5%D1%87%D0%B0_%D0%B7%D0%B0%D0%B6%D0%B8%D0%B3%D0%B0%D0%BD%D0%B8%D1%8F" title="Свеча зажигания – Russian" lang="ru" hreflang="ru" data-title="Свеча зажигания" data-language-autonym="Русский" data-language-local-name="Russian" class="interlanguage-link-target"><span>Русский</span></a></li><li class="interlanguage-link interwiki-sco mw-list-item"><a href="https://sco.wikipedia.org/wiki/Spark_plug" title="Spark plug – Scots" lang="sco" hreflang="sco" data-title="Spark plug" data-language-autonym="Scots" data-language-local-name="Scots" class="interlanguage-link-target"><span>Scots</span></a></li><li class="interlanguage-link interwiki-simple mw-list-item"><a href="https://simple.wikipedia.org/wiki/Spark_plug" title="Spark plug – Simple English" lang="en-simple" hreflang="en-simple" data-title="Spark plug" data-language-autonym="Simple English" data-language-local-name="Simple English" class="interlanguage-link-target"><span>Simple English</span></a></li><li class="interlanguage-link interwiki-sk mw-list-item"><a href="https://sk.wikipedia.org/wiki/Zapa%C4%BEovacia_svie%C4%8Dka" title="Zapaľovacia sviečka – Slovak" lang="sk" hreflang="sk" data-title="Zapaľovacia sviečka" data-language-autonym="Slovenčina" data-language-local-name="Slovak" class="interlanguage-link-target"><span>Slovenčina</span></a></li><li class="interlanguage-link interwiki-sl mw-list-item"><a href="https://sl.wikipedia.org/wiki/V%C5%BEigalna_sve%C4%8Dka" title="Vžigalna svečka – Slovenian" lang="sl" hreflang="sl" data-title="Vžigalna svečka" data-language-autonym="Slovenščina" data-language-local-name="Slovenian" class="interlanguage-link-target"><span>Slovenščina</span></a></li><li class="interlanguage-link interwiki-ckb mw-list-item"><a href="https://ckb.wikipedia.org/wiki/%D9%BE%D9%84%D8%A7%DA%A9%DB%8C_%D9%BE%D8%B1%DB%8C%D8%B4%DA%A9%D8%AF%D8%A7%D8%B1" title="پلاکی پریشکدار – Central Kurdish" lang="ckb" hreflang="ckb" data-title="پلاکی پریشکدار" data-language-autonym="کوردی" data-language-local-name="Central Kurdish" class="interlanguage-link-target"><span>کوردی</span></a></li><li class="interlanguage-link interwiki-sr mw-list-item"><a href="https://sr.wikipedia.org/wiki/%D0%A1%D0%B2%D0%B5%D1%9B%D0%B8%D1%86%D0%B0" title="Свећица – Serbian" lang="sr" hreflang="sr" data-title="Свећица" data-language-autonym="Српски / srpski" data-language-local-name="Serbian" class="interlanguage-link-target"><span>Српски / srpski</span></a></li><li class="interlanguage-link interwiki-sh mw-list-item"><a href="https://sh.wikipedia.org/wiki/Svje%C4%87ica" title="Svjećica – Serbo-Croatian" lang="sh" hreflang="sh" data-title="Svjećica" data-language-autonym="Srpskohrvatski / српскохрватски" data-language-local-name="Serbo-Croatian" class="interlanguage-link-target"><span>Srpskohrvatski / српскохрватски</span></a></li><li class="interlanguage-link interwiki-fi mw-list-item"><a href="https://fi.wikipedia.org/wiki/Sytytystulppa" 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class="mw-content-ltr mw-parser-output" lang="en" dir="ltr"><div class="shortdescription nomobile noexcerpt noprint searchaux" style="display:none">Device that generates sparks in internal combustion engines</div> <style data-mw-deduplicate="TemplateStyles:r1236090951">.mw-parser-output .hatnote{font-style:italic}.mw-parser-output div.hatnote{padding-left:1.6em;margin-bottom:0.5em}.mw-parser-output .hatnote i{font-style:normal}.mw-parser-output .hatnote+link+.hatnote{margin-top:-0.5em}@media print{body.ns-0 .mw-parser-output .hatnote{display:none!important}}</style><div role="note" class="hatnote navigation-not-searchable">For other uses, see <a href="/wiki/Spark_plug_(disambiguation)" class="mw-disambig" title="Spark plug (disambiguation)">Spark plug (disambiguation)</a>.</div> <figure class="mw-default-size mw-halign-right" typeof="mw:File/Thumb"><a href="/wiki/File:Sparkplug.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/6/6a/Sparkplug.jpg" decoding="async" width="120" height="415" class="mw-file-element" data-file-width="120" data-file-height="415" /></a><figcaption>Spark plug with single side electrode</figcaption></figure> <figure class="mw-default-size mw-halign-right" typeof="mw:File/Thumb"><a href="/wiki/File:Spark-plug01.jpeg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/c/c3/Spark-plug01.jpeg/220px-Spark-plug01.jpeg" decoding="async" width="220" height="221" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/c/c3/Spark-plug01.jpeg/330px-Spark-plug01.jpeg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/c/c3/Spark-plug01.jpeg/440px-Spark-plug01.jpeg 2x" data-file-width="1000" data-file-height="1005" /></a><figcaption>An <a href="/wiki/Electric_spark" title="Electric spark">electric spark</a> on the spark plug</figcaption></figure><p> A <b>spark plug</b> (sometimes, in <a href="/wiki/British_English" title="British English">British English</a>, a <b>sparking plug</b>,<sup id="cite_ref-1" class="reference"><a href="#cite_note-1"><span class="cite-bracket">[</span>1<span class="cite-bracket">]</span></a></sup> and, colloquially, a <b>plug</b>) is a device for delivering <a href="/wiki/Electric_current" title="Electric current">electric current</a> from an <a href="/wiki/Ignition_system" title="Ignition system">ignition system</a> to the <a href="/wiki/Combustion_chamber" title="Combustion chamber">combustion chamber</a> of a <a href="/wiki/Spark-ignition_engine" title="Spark-ignition engine">spark-ignition engine</a> to ignite the compressed fuel/air mixture by an <a href="/wiki/Electric_spark" title="Electric spark">electric spark</a>, while containing combustion pressure within the engine. A spark plug has a metal <a href="/wiki/Screw_thread" title="Screw thread">threaded</a> shell, electrically isolated from a central <a href="/wiki/Electrode" title="Electrode">electrode</a> by a <a href="/wiki/Ceramic" title="Ceramic">ceramic</a> insulator. The central electrode, which may contain a <a href="/wiki/Resistor" title="Resistor">resistor</a>, is connected by a heavily <a href="/wiki/Insulator_(electricity)" title="Insulator (electricity)">insulated</a> wire to the output terminal of an <a href="/wiki/Ignition_coil" title="Ignition coil">ignition coil</a> or <a href="/wiki/Ignition_magneto" title="Ignition magneto">magneto</a>. The spark plug's metal shell is screwed into the engine's <a href="/wiki/Cylinder_head" title="Cylinder head">cylinder head</a> and thus electrically <a href="/wiki/Ground_(electricity)" title="Ground (electricity)">grounded</a>. The central electrode protrudes through the porcelain insulator into the <a href="/wiki/Combustion_chamber" title="Combustion chamber">combustion chamber</a>, forming one or more <a href="/wiki/Spark_gap" title="Spark gap">spark gaps</a> between the inner end of the central electrode and usually one or more protuberances or structures attached to the inner end of the threaded shell and designated the <i>side</i>, <i>earth</i>, or <i>ground</i> electrode(s). </p><p>Spark plugs may also be used for other purposes; in <a href="/wiki/Saab_Direct_Ignition" title="Saab Direct Ignition">Saab Direct Ignition</a> when they are not firing, spark plugs are used to measure ionization in the cylinders – this ionic current measurement is used to replace the ordinary cam phase sensor, knock sensor and misfire measurement function.<sup id="cite_ref-2" class="reference"><a href="#cite_note-2"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup> Spark plugs may also be used in other applications such as furnaces wherein a combustible fuel/air mixture must be ignited. In this case, they are sometimes referred to as <b>flame igniters</b>.<sup class="noprint Inline-Template Template-Fact" style="white-space:nowrap;">[<i><a href="/wiki/Wikipedia:Citation_needed" title="Wikipedia:Citation needed"><span title="This claim needs references to reliable sources. (December 2011)">citation needed</span></a></i>]</sup> </p> <meta property="mw:PageProp/toc" /> <div class="mw-heading mw-heading2"><h2 id="History">History</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Spark_plug&action=edit&section=1" title="Edit section: History"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>In 1860 <a href="/wiki/%C3%89tienne_Lenoir" title="Étienne Lenoir">Étienne Lenoir</a> used an electric spark plug in his <a href="/wiki/Gas_engine" title="Gas engine">gas engine</a>, the first internal combustion piston engine. Lenoir is generally credited with the invention of the spark plug.<sup id="cite_ref-3" class="reference"><a href="#cite_note-3"><span class="cite-bracket">[</span>3<span class="cite-bracket">]</span></a></sup> <sup id="cite_ref-4" class="reference"><a href="#cite_note-4"><span class="cite-bracket">[</span>4<span class="cite-bracket">]</span></a></sup> </p><p>Early patents for spark plugs included those by <a href="/wiki/Nikola_Tesla" title="Nikola Tesla">Nikola Tesla</a> (in <span><a rel="nofollow" class="external text" href="https://patents.google.com/patent/US609250">U.S. patent 609,250</a></span> for an ignition timing system, 1898), <a href="/wiki/Frederick_Richard_Simms" title="Frederick Richard Simms">Frederick Richard Simms</a> (GB 24859/1898, 1898) and <a href="/wiki/Robert_Bosch" title="Robert Bosch">Robert Bosch</a> (GB 26907/1898). Only the invention of the first commercially viable high-voltage spark plug as part of a <a href="/wiki/Ignition_magneto" title="Ignition magneto">magneto</a>-based <a href="/wiki/Ignition_system" title="Ignition system">ignition system</a> by Robert Bosch's engineer <a href="/wiki/Gottlob_Honold" title="Gottlob Honold">Gottlob Honold</a> in 1902 made possible the development of the <a href="/wiki/Spark-ignition_engine" title="Spark-ignition engine">spark-ignition engine</a>. Subsequent manufacturing improvements can be credited to <a href="/wiki/Albert_Champion_(cyclist)" title="Albert Champion (cyclist)">Albert Champion</a>,<sup id="cite_ref-5" class="reference"><a href="#cite_note-5"><span class="cite-bracket">[</span>5<span class="cite-bracket">]</span></a></sup> to the <a href="/wiki/Alexander_Lodge" title="Alexander Lodge">Lodge brothers</a>, sons of Sir <a href="/wiki/Oliver_Lodge" title="Oliver Lodge">Oliver Lodge</a>, who developed and manufactured their father's idea<sup id="cite_ref-6" class="reference"><a href="#cite_note-6"><span class="cite-bracket">[</span>6<span class="cite-bracket">]</span></a></sup> and also to <a href="/wiki/Kenelm_Lee_Guinness" title="Kenelm Lee Guinness">Kenelm Lee Guinness</a>, of the <a href="/wiki/Guinness_family" title="Guinness family">Guinness brewing family</a>, who developed the KLG brand. Helen Blair Bartlett played a vital role in making the insulator in 1930.<sup id="cite_ref-7" class="reference"><a href="#cite_note-7"><span class="cite-bracket">[</span>7<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading2"><h2 id="Operation">Operation</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Spark_plug&action=edit&section=2" title="Edit section: Operation"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <figure class="mw-default-size mw-halign-right" typeof="mw:File/Thumb"><a href="/wiki/File:Four_stroke_engine_diagram.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/4/47/Four_stroke_engine_diagram.jpg/220px-Four_stroke_engine_diagram.jpg" decoding="async" width="220" height="248" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/4/47/Four_stroke_engine_diagram.jpg/330px-Four_stroke_engine_diagram.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/4/47/Four_stroke_engine_diagram.jpg/440px-Four_stroke_engine_diagram.jpg 2x" data-file-width="533" data-file-height="600" /></a><figcaption>Components of a typical, <a href="/wiki/Four_stroke_cycle" class="mw-redirect" title="Four stroke cycle">four stroke cycle</a>, <a href="/wiki/DOHC" class="mw-redirect" title="DOHC">DOHC</a> piston engine.<div><ul><li>(E) Exhaust <a href="/wiki/Camshaft" title="Camshaft">camshaft</a></li><li>(I) Intake camshaft</li><li><b>(S) Spark plug</b></li><li>(V) <a href="/wiki/Poppet_valve" title="Poppet valve">Valves</a></li><li>(P) <a href="/wiki/Piston" title="Piston">Piston</a></li><li>(R) <a href="/wiki/Connecting_rod" title="Connecting rod">Connecting rod</a></li><li>(C) <a href="/wiki/Crankshaft" title="Crankshaft">Crankshaft</a></li><li>(W) Water jacket for coolant flow</li></ul></div></figcaption></figure> <p>The function of a spark plug is to produce a spark at the required time to ignite the combustible mixture. The plug is connected to the high voltage generated by an <a href="/wiki/Ignition_coil" title="Ignition coil">ignition coil</a> or <a href="/wiki/Ignition_magneto" title="Ignition magneto">magneto</a>. As current flows from the coil, a voltage develops between the central and side electrodes. Initially no current can flow because the fuel and air in the gap is an insulator, but as the voltage rises further it begins to change the structure of the gases between the electrodes. Once the voltage exceeds the <a href="/wiki/Dielectric_strength" title="Dielectric strength">dielectric strength</a> of the gases, the gases become <a href="/wiki/Ionized" class="mw-redirect" title="Ionized">ionized</a>. The ionized gas becomes a conductor and allows current to flow across the gap. Spark plugs usually require voltage of 12,000–25,000 volts or more to "fire" properly, although it can go up to 45,000 volts. They supply higher current during the discharge process, resulting in a hotter and longer-duration spark. </p><p>As the current of electrons surges across the gap, it raises the temperature of the spark channel to 60,000 <a href="/wiki/Kelvin" title="Kelvin">K</a>. The intense heat in the spark channel causes the ionized gas to expand very quickly, like a small explosion. This is the "click" heard when observing a spark, similar to <a href="/wiki/Lightning" title="Lightning">lightning</a> and <a href="/wiki/Thunder" title="Thunder">thunder</a>. </p><p>The heat and pressure force the gases to react with each other, and at the end of the spark event there should be a small ball of fire in the <a href="/wiki/Spark_gap" title="Spark gap">spark gap</a> as the gases burn on their own. The size of this fireball, or kernel, depends on the exact composition of the mixture between the electrodes and the level of combustion chamber turbulence at the time of the spark. A small kernel will make the engine run as though the <a href="/wiki/Ignition_timing" title="Ignition timing">ignition timing</a> was delayed, and a large one as though the timing was advanced.<sup class="noprint Inline-Template Template-Fact" style="white-space:nowrap;">[<i><a href="/wiki/Wikipedia:Citation_needed" title="Wikipedia:Citation needed"><span title="This claim needs references to reliable sources. (June 2022)">citation needed</span></a></i>]</sup> </p> <div class="mw-heading mw-heading2"><h2 id="Spark_plug_construction">Spark plug construction</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Spark_plug&action=edit&section=3" title="Edit section: Spark plug construction"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>A spark plug is composed of a shell, insulator and the central conductor. It passes through the wall of the <a href="/wiki/Combustion_chamber" title="Combustion chamber">combustion chamber</a> and therefore must also seal the combustion chamber against high pressures and temperatures without deteriorating over long periods of time and extended use. </p><p>Spark plugs are specified by size, either thread or nut (often referred to as <i>Euro</i>), sealing type (taper or crush washer), and spark gap. Common thread (nut) sizes in Europe are 10 mm (16 mm), 14 mm (21 mm; sometimes, 16 mm), and 18 mm (24 mm, sometimes, 21 mm). In the United States, common thread (nut) sizes are 10mm (16mm), 12mm (14mm, 16mm or 17.5mm), 14mm (16mm, 20.63mm) and 18mm (20.63mm).<sup id="cite_ref-8" class="reference"><a href="#cite_note-8"><span class="cite-bracket">[</span>8<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading3"><h3 id="Parts_of_the_plug">Parts of the plug</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Spark_plug&action=edit&section=4" title="Edit section: Parts of the plug"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <div class="mw-heading mw-heading4"><h4 id="Terminal">Terminal</h4><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Spark_plug&action=edit&section=5" title="Edit section: Terminal"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>The top of the spark plug contains a terminal to connect to the <a href="/wiki/Ignition_system" title="Ignition system">ignition system</a>. Over of the years variations in the terminal configuration have been introduced by manufacturers. The exact terminal construction varies depending on the use of the spark plug. Most passenger car spark plug wires snap onto the terminal of the plug, but some wires have eyelet connectors which are fastened onto the plug under a nut. The standard solid non-removable nut SAE configuration is common for many cars and trucks. Plugs which are used for these applications often have the end of the terminal serve a double purpose as the nut on a thin threaded shaft so that they can be used for either type of connection. This type of spark plug has a removable nut or knurl, which enables its users to attach them to two different kinds of spark plug boots. Some spark plugs have a bare thread, which is a common type for motorcycles and ATVs. Finally, in very recent years, a cup-style terminal has been introduced, which allows for a longer ceramic insulator in the same confined space.<sup id="cite_ref-9" class="reference"><a href="#cite_note-9"><span class="cite-bracket">[</span>9<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading4"><h4 id="Insulator">Insulator</h4><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Spark_plug&action=edit&section=6" title="Edit section: Insulator"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>The main part of the insulator is typically made from <a href="/wiki/Sintered" class="mw-redirect" title="Sintered">sintered</a> <a href="/wiki/Alumina" class="mw-redirect" title="Alumina">alumina</a> (Al<sub>2</sub>O<sub>3</sub>),<sup id="cite_ref-10" class="reference"><a href="#cite_note-10"><span class="cite-bracket">[</span>10<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-11" class="reference"><a href="#cite_note-11"><span class="cite-bracket">[</span>11<span class="cite-bracket">]</span></a></sup> a very <a href="/wiki/Hardness" title="Hardness">hard</a> ceramic material with high <a href="/wiki/Dielectric_strength" title="Dielectric strength">dielectric strength</a>, printed with the manufacturer's name and identifying marks, then <a href="/wiki/Ceramic_glaze" title="Ceramic glaze">glazed</a> to improve resistance to surface spark tracking. Its major functions are to provide mechanical support and electrical insulation for the central electrode, while also providing an extended spark path for flashover protection. This extended portion, particularly in engines with deeply recessed plugs, helps extend the terminal above the cylinder head so as to make it more readily accessible. </p> <figure class="mw-default-size mw-halign-right" typeof="mw:File/Thumb"><a href="/wiki/File:Spark_plug_insulator.jpeg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/2/21/Spark_plug_insulator.jpeg/220px-Spark_plug_insulator.jpeg" decoding="async" width="220" height="165" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/2/21/Spark_plug_insulator.jpeg/330px-Spark_plug_insulator.jpeg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/2/21/Spark_plug_insulator.jpeg/440px-Spark_plug_insulator.jpeg 2x" data-file-width="1824" data-file-height="1368" /></a><figcaption>Dissected modern spark plug showing the one-piece <a href="/wiki/Sintered" class="mw-redirect" title="Sintered">sintered</a> <a href="/wiki/Alumina" class="mw-redirect" title="Alumina">alumina</a> insulator. The lower portion is unglazed.</figcaption></figure> <p>A further feature of sintered alumina is its good heat conduction – reducing the tendency for the insulator to glow with heat and so light the mixture prematurely. </p> <div class="mw-heading mw-heading4"><h4 id="Ribs">Ribs</h4><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Spark_plug&action=edit&section=7" title="Edit section: Ribs"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>By lengthening the surface between the high voltage terminal and the grounded metal case of the spark plug, the physical shape of the ribs functions to improve the electrical insulation and prevent electrical energy from leaking along the insulator surface from the terminal to the metal case. The disrupted and longer path makes the electricity encounter more resistance along the surface of the spark plug even in the presence of dirt and moisture. Some spark plugs are manufactured without ribs; improvements in the dielectric strength of the insulator make them less important.<sup class="noprint Inline-Template Template-Fact" style="white-space:nowrap;">[<i><a href="/wiki/Wikipedia:Citation_needed" title="Wikipedia:Citation needed"><span title="This claim needs references to reliable sources. (December 2011)">citation needed</span></a></i>]</sup> </p> <div class="mw-heading mw-heading4"><h4 id="Insulator_tip">Insulator tip</h4><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Spark_plug&action=edit&section=8" title="Edit section: Insulator tip"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <figure class="mw-default-size mw-halign-right" typeof="mw:File/Thumb"><a href="/wiki/File:Candela_rotta.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/e/e9/Candela_rotta.jpg/220px-Candela_rotta.jpg" decoding="async" width="220" height="141" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/e/e9/Candela_rotta.jpg/330px-Candela_rotta.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/e/e9/Candela_rotta.jpg/440px-Candela_rotta.jpg 2x" data-file-width="1280" data-file-height="823" /></a><figcaption> Two spark plugs in comparison views in multiple angles, one of which is consumed regularly, while the other has the insulating ceramic broken and the central electrode shortened, due to manufacturing defects and / or temperature swing</figcaption></figure> <p>On modern (post 1930s) spark plugs, the tip of the insulator protruding into the combustion chamber is the same sintered aluminium oxide (alumina) <a href="/wiki/Ceramic" title="Ceramic">ceramic</a> as the upper portion, merely unglazed. It is designed to withstand 650 °C (1,200 °F) and 60 kV. </p><p>Older spark plugs, particularly in aircraft, used an insulator made of stacked layers of <a href="/wiki/Mica" title="Mica">mica</a>, compressed by tension in the centre electrode. </p><p>With the development of <a href="/wiki/Tetraethyllead" title="Tetraethyllead">leaded petrol</a> in the 1930s, lead deposits on the mica became a problem and reduced the interval between needing to clean the spark plug. Sintered alumina was developed by <a href="/wiki/Siemens" title="Siemens">Siemens</a> in Germany to counteract this.<sup id="cite_ref-Banks_12-0" class="reference"><a href="#cite_note-Banks-12"><span class="cite-bracket">[</span>12<span class="cite-bracket">]</span></a></sup> Sintered alumina is a superior material to mica or porcelain because it is a relatively good thermal conductor for a ceramic, it maintains good mechanical strength and (thermal) shock resistance at higher temperatures, and this ability to run hot allows it to be run at "self cleaning" temperatures without rapid degradation. It also allows a simple single piece construction at low cost but high mechanical reliability. The dimensions of the insulator and the metal conductor core determine the <a href="#Heat_range">heat range</a> of the plug. Short insulators are usually "cooler" plugs, while "hotter" plugs are made with a lengthened path to the metal body, though this also depends on the thermally conductive metal core. </p> <div class="mw-heading mw-heading4"><h4 id="Seals">Seals</h4><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Spark_plug&action=edit&section=9" title="Edit section: Seals"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>Because the spark plug also <a href="/wiki/Seal_(mechanical)" title="Seal (mechanical)">seals</a> the combustion chamber of the engine when installed, seals are required to ensure there is no leakage from the combustion chamber. The internal seals of modern plugs are made of compressed glass/metal powder, but old style seals were typically made by the use of a multi-layer <a href="/wiki/Brazing" title="Brazing">braze</a>. The external seal is usually a <a href="/wiki/Crush_washer" class="mw-redirect" title="Crush washer">crush washer</a>, but some manufacturers use the cheaper method of a taper interface and simple compression to attempt sealing. </p> <div class="mw-heading mw-heading4"><h4 id="Metal_case/shell"><span id="Metal_case.2Fshell"></span>Metal case/shell</h4><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Spark_plug&action=edit&section=10" title="Edit section: Metal case/shell"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>The metal case/shell (or the <i>jacket</i>, as many people call it) of the spark plug withstands the torque of tightening the plug, serves to remove heat from the insulator and pass it on to the cylinder head, and acts as the ground for the sparks passing through the central electrode to the side electrode. Spark plug threads are cold rolled to prevent thermal cycle fatigue. It's important to install spark plugs with the correct "reach," or thread length. Spark plugs can vary in reach from 0.095 to 2.649 cm (0.0375 to 1.043 in), such for automotive and small engine applications.<sup id="cite_ref-13" class="reference"><a href="#cite_note-13"><span class="cite-bracket">[</span>13<span class="cite-bracket">]</span></a></sup> Also, a marine spark plug's shell is double-dipped, zinc-chromate coated metal.<sup id="cite_ref-14" class="reference"><a href="#cite_note-14"><span class="cite-bracket">[</span>14<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading4"><h4 id="Central_electrode">Central electrode</h4><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Spark_plug&action=edit&section=11" title="Edit section: Central electrode"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <figure class="mw-default-size mw-halign-right" typeof="mw:File/Thumb"><a href="/wiki/File:Bougie3.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/4/41/Bougie3.jpg/220px-Bougie3.jpg" decoding="async" width="220" height="220" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/4/41/Bougie3.jpg/330px-Bougie3.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/4/41/Bougie3.jpg/440px-Bougie3.jpg 2x" data-file-width="800" data-file-height="800" /></a><figcaption>Central and lateral electrodes</figcaption></figure> <p>The central electrode is connected to the terminal through an internal wire and commonly a ceramic series resistance to reduce emission of <a href="/wiki/Radio_frequency" title="Radio frequency">RF</a> noise from the sparking. Non-resistor spark plugs, commonly sold without an "R" in the plug type part number, lack this element to reduce electro-magnetic interference with radios and other sensitive equipment. The tip can be made of a combination of <a href="/wiki/Copper" title="Copper">copper</a>, <a href="/wiki/Nickel" title="Nickel">nickel</a>-<a href="/wiki/Iron" title="Iron">iron</a>, <a href="/wiki/Chromium" title="Chromium">chromium</a>, or <a href="/wiki/Noble_metal" title="Noble metal">noble metals</a>. </p><p>In the late 1970s, the development of engines reached a stage where the heat range of conventional spark plugs with solid nickel alloy centre electrodes was unable to cope with their demands. A plug that was cold enough to cope with the demands of high speed driving would not be able to burn off the carbon deposits caused by stop–start urban conditions, and would foul in these conditions, making the engine misfire. Similarly, a plug that was hot enough to run smoothly in town could melt when called upon to cope with extended high speed running on motorways. The answer to this problem, devised by the spark plug manufacturers, was to use a different material and design for the centre electrode that would be able to carry the heat of combustion away from the tip more effectively than a solid nickel alloy could. Copper was the material chosen for the task and a method for manufacturing the copper-cored centre electrode was created by <a href="/w/index.php?title=Floform&action=edit&redlink=1" class="new" title="Floform (page does not exist)">Floform</a>. </p><p>The central electrode is usually the one designed to eject the electrons (the <a href="/wiki/Cathode" title="Cathode">cathode</a>, i.e. negative polarity<sup id="cite_ref-Hillier,_Spark_plug_15-0" class="reference"><a href="#cite_note-Hillier,_Spark_plug-15"><span class="cite-bracket">[</span>15<span class="cite-bracket">]</span></a></sup> relative to the engine block) because it is normally the hottest part of the plug; it is easier to emit electrons from a hot surface, because of the same physical laws that increase emissions of vapor from hot surfaces (see <a href="/wiki/Thermionic_emission" title="Thermionic emission">thermionic emission</a>).<sup id="cite_ref-ih_16-0" class="reference"><a href="#cite_note-ih-16"><span class="cite-bracket">[</span>16<span class="cite-bracket">]</span></a></sup> In addition, electrons are emitted where the electrical field strength is greatest; this is from wherever the radius of curvature of the surface is smallest, from a sharp point or edge rather than a flat surface (see <a href="/wiki/Corona_discharge" title="Corona discharge">corona discharge</a>).<sup id="cite_ref-ih_16-1" class="reference"><a href="#cite_note-ih-16"><span class="cite-bracket">[</span>16<span class="cite-bracket">]</span></a></sup> Using the colder, blunter side electrode as negative requires up to 45 percent higher voltage,<sup id="cite_ref-ih_16-2" class="reference"><a href="#cite_note-ih-16"><span class="cite-bracket">[</span>16<span class="cite-bracket">]</span></a></sup> so few ignition systems aside from <a href="/wiki/Wasted_spark" class="mw-redirect" title="Wasted spark">wasted spark</a> are designed this way.<sup id="cite_ref-wastedspark_17-0" class="reference"><a href="#cite_note-wastedspark-17"><span class="cite-bracket">[</span>17<span class="cite-bracket">]</span></a></sup> Waste spark systems place a greater strain upon spark plugs since they alternately fire electrons in both directions (from the ground electrode to the central electrode, not just from the central electrode to the ground electrode). As a result, vehicles with such a system should have precious metals on both electrodes, not just on the central electrode, in order to increase service replacement intervals since they wear down the metal more quickly in both directions, not just one.<sup id="cite_ref-18" class="reference"><a href="#cite_note-18"><span class="cite-bracket">[</span>18<span class="cite-bracket">]</span></a></sup> </p><p>It would be easiest to pull electrons from a pointed electrode but a pointed electrode would erode after only a few seconds. Instead, the electrons emit from the sharp edges of the end of the electrode; as these edges erode, the spark becomes weaker and less reliable. </p><p>At one time it was common to remove the spark plugs, clean deposits off the ends either manually or with specialized <a href="/wiki/Sandblasting" title="Sandblasting">sandblasting</a> equipment and file the end of the electrode to restore the sharp edges, but this practice has become less frequent for three reasons: </p> <ol><li>cleaning with tools such as a wire brush leaves traces of metal on the insulator which can provide a weak conduction path and thus weaken the spark (increasing emissions).</li> <li>plugs are so cheap relative to labor cost, economics dictate replacement, particularly with modern long-life plugs.</li> <li>iridium and platinum plugs that have longer lifetimes than copper have become more common.</li></ol> <p>The development of noble metal high temperature electrodes (using metals such as <a href="/wiki/Yttrium" title="Yttrium">yttrium</a>, <a href="/wiki/Iridium" title="Iridium">iridium</a>, <a href="/wiki/Tungsten" title="Tungsten">tungsten</a>, <a href="/wiki/Palladium" title="Palladium">palladium</a>, or <a href="/wiki/Ruthenium" title="Ruthenium">ruthenium</a>, as well as the relatively high value <a href="/wiki/Platinum" title="Platinum">platinum</a>, <a href="/wiki/Silver" title="Silver">silver</a> or <a href="/wiki/Gold" title="Gold">gold</a>) allows the use of a smaller center wire, which has sharper edges but will not melt or corrode away. These materials are used because of their high melting points and durability, not because of their electrical conductivity (which is irrelevant in series with the plug resistor or wires). The smaller electrode also absorbs less heat from the spark and initial flame energy. </p><p><a href="/wiki/Polonium" title="Polonium">Polonium</a> spark plugs were marketed by <a href="/wiki/Firestone_Tire_and_Rubber_Company" title="Firestone Tire and Rubber Company">Firestone</a> from 1940 to 1953. While the amount of radiation from the plugs was minuscule and not a threat to the consumer, the benefits of such plugs quickly diminished after approximately a month because of polonium's short half-life, and because buildup on the conductors would block the radiation that improved engine performance. The premise behind the polonium spark plug, as well as <a href="/wiki/Alfred_Matthew_Hubbard" title="Alfred Matthew Hubbard">Alfred Matthew Hubbard</a>'s prototype <a href="/wiki/Radium" title="Radium">radium</a> plug that preceded it, was that the radiation would improve ionization of the fuel in the cylinder and thus allow the plug to fire more quickly and efficiently.<sup id="cite_ref-19" class="reference"><a href="#cite_note-19"><span class="cite-bracket">[</span>19<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-20" class="reference"><a href="#cite_note-20"><span class="cite-bracket">[</span>20<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading4"><h4 id="Side_(ground,_earth)_electrode"><span id="Side_.28ground.2C_earth.29_electrode"></span>Side (ground, earth) electrode</h4><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Spark_plug&action=edit&section=12" title="Edit section: Side (ground, earth) electrode"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>The side electrode (also known as the "ground strap") is made from high nickel <a href="/wiki/Steel" title="Steel">steel</a> and is welded or hot forged to the side of the metal shell. The side electrode also runs very hot, especially on projected nose plugs. Some designs have provided a copper core to this electrode, so as to increase heat conduction. Multiple side electrodes may also be used, so that they don't overlap the central electrode. The ground electrode can also have small pads of platinum or even iridium added to them in order to increase service life.<sup id="cite_ref-21" class="reference"><a href="#cite_note-21"><span class="cite-bracket">[</span>21<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading3"><h3 id="Spark_plug_gap">Spark plug gap</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Spark_plug&action=edit&section=13" title="Edit section: Spark plug gap"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <figure class="mw-default-size mw-halign-right" typeof="mw:File/Thumb"><a href="/wiki/File:Spark_plug_gauge.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/b/bf/Spark_plug_gauge.jpg" decoding="async" width="200" height="200" class="mw-file-element" data-file-width="200" data-file-height="200" /></a><figcaption><i>Gap gauge:</i> A disk with a tapered edge; the edge is thicker going counter-clockwise, and a spark plug will be hooked along the edge to check the gap.</figcaption></figure> <p>Spark plugs are typically designed to have a spark gap which can be adjusted by the technician installing the spark plug, by bending the ground electrode slightly. The same plug may be specified for several different engines, requiring a different gap for each. Spark plugs in automobiles generally have a gap between 0.6 and 1.8 mm (0.024 and 0.071 in). The gap may require adjustment from the out-of-the-box gap. </p><p>A <i>spark plug gap <a href="/wiki/Gauge_(engineering)" class="mw-redirect" title="Gauge (engineering)">gauge</a></i> is a disc with a sloping edge, or with round wires of precise diameters, and is used to measure the gap. Use of a <a href="/wiki/Feeler_gauge" title="Feeler gauge">feeler gauge</a> with flat blades instead of round wires, as is used on <a href="/wiki/Distributor" title="Distributor">distributor</a> points or <a href="/wiki/Poppet_valve" title="Poppet valve">valve</a> lash, will give erroneous results, due to the shape of spark plug electrodes.<sup class="noprint Inline-Template Template-Fact" style="white-space:nowrap;">[<i><a href="/wiki/Wikipedia:Citation_needed" title="Wikipedia:Citation needed"><span title="This claim needs references to reliable sources. (May 2012)">citation needed</span></a></i>]</sup> The simplest gauges are a collection of keys of various thicknesses which match the desired gaps and the gap is adjusted until the key fits snugly. With current engine technology, universally incorporating solid state ignition systems and computerized <a href="/wiki/Fuel_injection" title="Fuel injection">fuel injection</a>, the gaps used are larger on average than in the era of <a href="/wiki/Carburetor" title="Carburetor">carburetors</a> and breaker point distributors, to the extent that spark plug gauges from that era cannot always measure the required gaps of current cars.<sup class="noprint Inline-Template Template-Fact" style="white-space:nowrap;">[<i><a href="/wiki/Wikipedia:Citation_needed" title="Wikipedia:Citation needed"><span title="This claim needs references to reliable sources. (April 2012)">citation needed</span></a></i>]</sup><sup id="cite_ref-22" class="reference"><a href="#cite_note-22"><span class="cite-bracket">[</span>22<span class="cite-bracket">]</span></a></sup> Vehicles using compressed natural gas generally require narrower gaps than vehicles using gasoline.<sup id="cite_ref-23" class="reference"><a href="#cite_note-23"><span class="cite-bracket">[</span>23<span class="cite-bracket">]</span></a></sup> </p><p>The gap adjustment (also called "spark plug gapping") can be crucial to proper engine operation. A narrow gap may give too small and weak a spark to effectively ignite the fuel-air mixture, but the plug will almost always fire on each cycle. A gap that is too wide might prevent a spark from firing at all or may misfire at high speeds, but will usually have a spark that is strong for a clean burn. A spark which intermittently fails to ignite the fuel-air mixture may not be noticeable directly, but will show up as a reduction in the engine's power and <a href="/wiki/Fuel_efficiency" title="Fuel efficiency">fuel efficiency</a>. Gap adjustment is not recommended for iridium and platinum spark plugs, because there is a risk of damaging a metal disk welded to the electrode.<sup id="cite_ref-24" class="reference"><a href="#cite_note-24"><span class="cite-bracket">[</span>24<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading3"><h3 id="Variations_on_the_basic_design">Variations on the basic design</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Spark_plug&action=edit&section=14" title="Edit section: Variations on the basic design"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:Sparkplug3.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/b/b6/Sparkplug3.jpg/110px-Sparkplug3.jpg" decoding="async" width="110" height="360" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/b/b6/Sparkplug3.jpg/165px-Sparkplug3.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/b/b6/Sparkplug3.jpg/220px-Sparkplug3.jpg 2x" data-file-width="440" data-file-height="1439" /></a><figcaption>Spark plug with two side (ground) electrodes</figcaption></figure> <p>Over the years variations on the basic spark plug design have attempted to provide either better ignition, longer life, or both. Such variations include the use of two, three, or four equally spaced ground electrodes surrounding the central electrode. Other variations include using a recessed central electrode surrounded by the spark plug thread, which effectively becomes the ground electrode (see "surface-discharge spark plug", below). Also there is the use of a V-shaped notch in the tip of the ground electrode. Multiple ground electrodes generally provide longer life, as when the spark gap widens due to electric discharge wear, the spark moves to another closer ground electrode. The disadvantage of multiple ground electrodes is that a shielding effect can occur in the engine combustion chamber inhibiting the flame face as the fuel air mixture burns. This can result in a less efficient burn and increased fuel consumption. They also are difficult or nearly impossible to adjust to another uniform gap size. </p> <div class="mw-heading mw-heading3"><h3 id="Surface-discharge_spark_plug">Surface-discharge spark plug</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Spark_plug&action=edit&section=15" title="Edit section: Surface-discharge spark plug"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>A piston engine has a part of the combustion chamber that is always out of reach of the piston; and this zone is where the conventional spark plug is located. A <a href="/wiki/Wankel_engine" title="Wankel engine">Wankel engine</a> has a permanently varying combustion area; and the spark plug is inevitably swept by the rotor's apex seals. If a spark plug were to protrude into the Wankel's combustion chamber it would be hit by the passing apex seal, but if the plug were recessed to avoid this, mixture access to the spark would be reduced, leading to misfire or incomplete combustion. So a new type of "surface discharge" plug was developed, presenting an almost flat face to the combustion chamber. A stubby centre electrode projects only very slightly, and the entire earthed body of the plug acts as the side electrode. The electrodes thus sit just beyond the reach of the passing apex seal, while the spark is accessible to the fuel/air mixture. The arc gap remains constant throughout the entire service life of a surface-gap spark plug, <span class="citation-needed-content" style="padding-left:0.1em; padding-right:0.1em; color:var(--color-subtle, #54595d); border:1px solid var(--border-color-subtle, #c8ccd1);">and the spark path will continually vary (instead of darting from the centre to the side electrode as in a conventional plug).</span><sup class="noprint Inline-Template Template-Fact" style="margin-left:0.1em; white-space:nowrap;">[<i><a href="/wiki/Wikipedia:Citation_needed" title="Wikipedia:Citation needed"><span title="This claim needs references to reliable sources. (March 2021)">citation needed</span></a></i>]</sup> A further advantage of the surface-gap design is that the side electrode cannot break off and potentially cause engine damage, though this also doesn't often happen with conventional spark plugs.<sup class="noprint Inline-Template Template-Fact" style="white-space:nowrap;">[<i><a href="/wiki/Wikipedia:Citation_needed" title="Wikipedia:Citation needed"><span title="This claim needs references to reliable sources. (March 2021)">citation needed</span></a></i>]</sup> </p> <div class="mw-heading mw-heading3"><h3 id="Sealing_to_the_cylinder_head">Sealing to the cylinder head</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Spark_plug&action=edit&section=16" title="Edit section: Sealing to the cylinder head"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:Spark_plugs_old_and_replacement_7058.JPG" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/1/16/Spark_plugs_old_and_replacement_7058.JPG/220px-Spark_plugs_old_and_replacement_7058.JPG" decoding="async" width="220" height="140" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/1/16/Spark_plugs_old_and_replacement_7058.JPG/330px-Spark_plugs_old_and_replacement_7058.JPG 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/1/16/Spark_plugs_old_and_replacement_7058.JPG/440px-Spark_plugs_old_and_replacement_7058.JPG 2x" data-file-width="2256" data-file-height="1437" /></a><figcaption>Old spark plug removed from a car, new one ready to install.</figcaption></figure> <p>Most spark plugs seal to the cylinder head with a single-use hollow or folded metal washer which is crushed slightly between the flat surface of the head and that of the plug, just above the threads. Some spark plugs have a tapered seat that uses no washer. The torque for installing these plugs is supposed to be lower than a washer-sealed plug.<sup id="cite_ref-25" class="reference"><a href="#cite_note-25"><span class="cite-bracket">[</span>25<span class="cite-bracket">]</span></a></sup> Spark plugs with tapered seats should never be installed in vehicles with heads requiring washers, and vice versa. Otherwise, a poor seal or incorrect reach would result because of the threads not properly seating in the heads. </p> <div class="mw-heading mw-heading3"><h3 id="Tip_protrusion">Tip protrusion</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Spark_plug&action=edit&section=17" title="Edit section: Tip protrusion"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <figure class="mw-default-size mw-halign-right" typeof="mw:File/Thumb"><a href="/wiki/File:67d2scd.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/2/21/67d2scd.jpg/220px-67d2scd.jpg" decoding="async" width="220" height="164" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/2/21/67d2scd.jpg/330px-67d2scd.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/2/21/67d2scd.jpg/440px-67d2scd.jpg 2x" data-file-width="480" data-file-height="358" /></a><figcaption>Different spark plug sizes. The left and right plug are identical in threading, electrodes, tip protrusion, and heat range. The centre plug is a compact variant, with smaller hex and porcelain portions outside the head, to be used where space is limited. The rightmost plug has a longer threaded portion, to be used in a thicker <a href="/wiki/Cylinder_head" title="Cylinder head">cylinder head</a>.</figcaption></figure><p> The length of the threaded portion of the plug should be closely matched to the thickness of the head. If a plug extends too far into the combustion chamber, it may be struck by the piston, damaging the engine internally. Less dramatically, if the threads of the plug extend into the combustion chamber, the sharp edges of the threads act as point sources of heat which may cause <a href="/wiki/Pre-ignition" title="Pre-ignition">pre-ignition</a>; in addition, deposits which form between the exposed threads may make it difficult to remove the plugs, even damaging the threads on aluminium heads in the process of removal. </p><p>The protrusion of the tip into the chamber also affects plug performance, however; the more centrally located the spark gap is, generally the better the ignition of the air-fuel mixture will be, although experts believe the process is more complex and dependent on combustion chamber shape. On the other hand, if an engine is "burning oil", the excess oil leaking into the combustion chamber tends to foul the plug tip and inhibit the spark; in such cases, a plug with less protrusion than the engine would normally call for often collects less <a href="/wiki/Fouling" title="Fouling">fouling</a> and performs better, for a longer period. Special "anti-fouling" adapters are sold which fit between the plug and the head to reduce the protrusion of the plug for just this reason, on older engines with severe oil burning problems; this will cause the ignition of the fuel-air mixture to be less effective, but in such cases, this is of lesser significance. </p> <div class="mw-heading mw-heading2"><h2 id="Heat_range">Heat range</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Spark_plug&action=edit&section=18" title="Edit section: Heat range"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <figure class="mw-default-size mw-halign-right" typeof="mw:File/Thumb"><a href="/wiki/File:Spark_plug_heat.svg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/5/55/Spark_plug_heat.svg/220px-Spark_plug_heat.svg.png" decoding="async" width="220" height="175" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/5/55/Spark_plug_heat.svg/330px-Spark_plug_heat.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/5/55/Spark_plug_heat.svg/440px-Spark_plug_heat.svg.png 2x" data-file-width="483" data-file-height="384" /></a><figcaption>Construction of hot and cold spark plugs – a longer insulator tip makes the plug hotter</figcaption></figure> <p>The <a href="/wiki/Operating_temperature" title="Operating temperature">operating temperature</a> of a spark plug is the actual physical <a href="/wiki/Temperature" title="Temperature">temperature</a> at the tip of the spark plug within the running engine, normally between 500 and 800 °C (932 and 1,472 °F). This is important because it determines the efficiency of plug self-cleaning and is determined by a number of factors, but primarily the actual temperature within the combustion chamber. There is no direct relationship between the actual operating temperature of the spark plug and spark voltage. However, the level of <a href="/wiki/Torque" title="Torque">torque</a> currently being produced by the engine will strongly influence spark plug operating temperature because the maximal temperature and pressure occur when the engine is operating near peak torque output (torque and rotational speed directly determine the <a href="/wiki/Power_(physics)" title="Power (physics)">power</a> output). The temperature of the insulator responds to the thermal conditions it is exposed to in the combustion chamber, but not vice versa. If the tip of the spark plug is too hot, it can cause pre-ignition or sometimes <a href="/wiki/Engine_knocking" title="Engine knocking">detonation/knocking</a>, and damage may occur. If it is too cold, electrically conductive deposits may form on the insulator, causing a loss of spark energy or the actual shorting-out of the spark current. </p><p>A spark plug is said to be "hot" if it is a better heat insulator, keeping more heat in the tip of the spark plug. A spark plug is said to be "cold" if it can conduct more heat out of the spark plug tip and lower the tip's temperature. Whether a spark plug is "hot" or "cold" is known as the heat range of the spark plug. The heat range of a spark plug is typically specified as a number, with some manufacturers using ascending numbers for hotter plugs, and others doing the opposite – using ascending numbers for colder plugs. </p><p>The heat range of a spark plug is affected by the construction of the spark plug: the types of materials used, the length of <a href="/wiki/Electrical_insulation" class="mw-redirect" title="Electrical insulation">insulator</a> and the <a href="/wiki/Surface_area" title="Surface area">surface area</a> of the plug exposed within the combustion chamber. For normal use, the selection of a spark plug heat range is a balance between keeping the tip hot enough at idle to prevent fouling and cold enough at maximal power to prevent pre-ignition or <a href="/wiki/Engine_knocking" title="Engine knocking">engine knocking</a>. By examining "hotter" and "cooler" spark plugs of the same manufacturer side by side, the principle involved can be very clearly seen; the cooler plugs have a more substantial ceramic insulator filling the gap between the center electrode and the shell, effectively allowing more heat to be carried off by the shell, while the hotter plugs have less ceramic material, so that the tip is more isolated from the body of the plug and retains heat better. </p><p><a href="/wiki/Heat" title="Heat">Heat</a> from the combustion chamber escapes through the exhaust gases, the side walls of the cylinder and the spark plug itself. The heat range of a spark plug has only a minute effect on combustion chamber and overall engine temperature. A cold plug will not materially cool down an engine's running temperature. (A too hot plug may, however, indirectly lead to a runaway pre-ignition condition that <i>can</i> increase engine temperature.) Rather, the main effect of a "hot" or "cold" plug is to affect the temperature of the tip of the spark plug. </p><p>It was common before the modern era of computerized fuel injection to specify at least a couple of different heat ranges for plugs for an automobile engine; a hotter plug for cars that were mostly driven slowly around the city, and a colder plug for sustained high-speed highway use. This practice has, however, largely become obsolete now that cars' fuel/air mixtures and cylinder temperatures are maintained within a narrow range, for purposes of limiting emissions. Racing engines, however, still benefit from picking a proper plug heat range. Very old racing engines will sometimes have two sets of plugs, one just for starting and another to be installed for driving once the engine is warmed up. </p><p>Spark plug manufacturers use different numbers to denote heat range of their spark plugs. Some manufacturers, such as Denso and NGK, have numbers that become higher as they get colder. By contrast, Champion, Bosch, BRISK, Beru, and ACDelco use a heat range system in which the numbers become bigger as the plugs get hotter. As a result, heat range numbers need to be translated between the different manufacturers and cannot be casually interchanged as equals. </p> <div class="mw-heading mw-heading2"><h2 id="Reading_spark_plugs">Reading spark plugs</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Spark_plug&action=edit&section=19" title="Edit section: Reading spark plugs"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>The spark plug's firing end will be affected by the internal environment of the combustion chamber. As the spark plug can be removed for inspection, the effects of combustion on the plug can be examined. An examination, or "reading" of the characteristic markings on the firing end of the spark plug can indicate conditions within the running engine. Engine and spark plug manufacturers will publish information about the characteristic markings in spark plug reading charts. </p><p>A light brownish discoloration of the tip of the block indicates proper operation; other conditions may indicate malfunction. For example, a sandblasted look to the tip of the spark plug means persistent, light <a href="/wiki/Engine_knocking" title="Engine knocking">detonation</a> is occurring, often unheard. The damage that is occurring to the tip of the spark plug is also occurring on the inside of the cylinder. Heavy detonation can cause outright breakage of the spark plug insulator and internal engine parts before appearing as sandblasted erosion but is easily heard. As another example, if the plug is too cold, there will be deposits on the nose of the plug. Conversely if the plug is too hot, the porcelain will be porous looking, almost like sugar. The material which seals the central electrode to the insulator will boil out. Sometimes the end of the plug will appear glazed, as the deposits have melted. </p><p>An idling engine will have a different impact on the spark plugs than one running at full <a href="/wiki/Throttle" title="Throttle">throttle</a>. Spark plug readings are only valid for the most recent engine operating conditions and running the engine under different conditions may erase or obscure characteristic marks previously left on the spark plugs. The most valuable information is gathered by running the engine at high speed and full load, immediately cutting the ignition off and stopping without idling or low speed operation and removing the plugs for reading.<sup class="noprint Inline-Template Template-Fact" style="white-space:nowrap;">[<i><a href="/wiki/Wikipedia:Citation_needed" title="Wikipedia:Citation needed"><span title="Who decided this method works the best? (August 2014)">citation needed</span></a></i>]</sup> </p><p>Spark plug reading viewers, which are simply combined flashlight/magnifiers, are available to improve the reading of the spark plugs. </p> <figure class="mw-default-size mw-halign-right" typeof="mw:File/Thumb"><a href="/wiki/File:2spark_plug_viewers.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/f/fb/2spark_plug_viewers.jpg/220px-2spark_plug_viewers.jpg" decoding="async" width="220" height="136" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/f/fb/2spark_plug_viewers.jpg/330px-2spark_plug_viewers.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/f/fb/2spark_plug_viewers.jpg/440px-2spark_plug_viewers.jpg 2x" data-file-width="500" data-file-height="308" /></a><figcaption>Two spark plug viewers</figcaption></figure> <div class="mw-heading mw-heading2"><h2 id="Indexing_spark_plugs">Indexing spark plugs</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Spark_plug&action=edit&section=20" title="Edit section: Indexing spark plugs"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>"Indexing" of plugs upon installation involves installing the spark plug so that the open area of its gap, not shrouded by the ground electrode, faces the center of the combustion chamber rather than one of its walls. The theory holds that this will maximize the exposure of the fuel-air mixture to the spark, also ensuring that every combustion chamber is even in layout and therefore resulting in better ignition. Indexing is accomplished by marking the location of the gap on the outside of the plug, installing it, and noting the direction in which the mark faces. Then the plug is removed and washers are added to change the orientation of the tightened plug. This must be done individually for each plug, as the orientation of the gap with respect to the threads of the shell is <a href="/wiki/Random" class="mw-redirect" title="Random">random</a>. Some plugs are made with a non-random orientation of the gap and are usually marked as such by a suffix to the model number; typically these are specified by manufacturers of very small engines where the spark plug tip and electrodes form a significantly large part of the shape of the combustion chamber. The <a href="/wiki/Honda_Insight" title="Honda Insight">Honda Insight</a> has indexed spark plugs from factory, with four different part numbers available corresponding to the different degrees of indexing to achieve most efficient combustion and maximal fuel efficiency.<sup class="noprint Inline-Template Template-Fact" style="white-space:nowrap;">[<i><a href="/wiki/Wikipedia:Citation_needed" title="Wikipedia:Citation needed"><span title="This claim needs references to reliable sources. (September 2017)">citation needed</span></a></i>]</sup> </p> <div class="mw-heading mw-heading2"><h2 id="See_also">See also</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Spark_plug&action=edit&section=21" title="Edit section: See also"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <ul><li><a href="/wiki/Coso_artifact" title="Coso artifact">Coso artifact</a></li> <li><a href="/wiki/Glow_plug_(diesel_engine)" class="mw-redirect" title="Glow plug (diesel engine)">Glow plug (diesel engine)</a></li> <li><a href="/wiki/Glow_plug_(model_engine)" title="Glow plug (model engine)">Glow plug (model engine)</a></li> <li><a href="/wiki/Hot-tube_ignitor" title="Hot-tube ignitor">Hot-tube ignitor</a></li> <li><a href="/wiki/List_of_auto_parts" title="List of auto parts">List of auto parts</a></li> <li><a href="/wiki/Ninja_rocks" title="Ninja rocks">Ninja rocks</a></li></ul> <div class="mw-heading mw-heading2"><h2 id="References">References</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Spark_plug&action=edit&section=22" title="Edit section: References"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <style data-mw-deduplicate="TemplateStyles:r1239543626">.mw-parser-output .reflist{margin-bottom:0.5em;list-style-type:decimal}@media screen{.mw-parser-output .reflist{font-size:90%}}.mw-parser-output .reflist .references{font-size:100%;margin-bottom:0;list-style-type:inherit}.mw-parser-output .reflist-columns-2{column-width:30em}.mw-parser-output .reflist-columns-3{column-width:25em}.mw-parser-output .reflist-columns{margin-top:0.3em}.mw-parser-output .reflist-columns ol{margin-top:0}.mw-parser-output .reflist-columns li{page-break-inside:avoid;break-inside:avoid-column}.mw-parser-output .reflist-upper-alpha{list-style-type:upper-alpha}.mw-parser-output .reflist-upper-roman{list-style-type:upper-roman}.mw-parser-output .reflist-lower-alpha{list-style-type:lower-alpha}.mw-parser-output .reflist-lower-greek{list-style-type:lower-greek}.mw-parser-output .reflist-lower-roman{list-style-type:lower-roman}</style><div class="reflist"> <div class="mw-references-wrap mw-references-columns"><ol class="references"> <li id="cite_note-1"><span class="mw-cite-backlink"><b><a href="#cite_ref-1">^</a></b></span> <span class="reference-text"><style data-mw-deduplicate="TemplateStyles:r1238218222">.mw-parser-output cite.citation{font-style:inherit;word-wrap:break-word}.mw-parser-output .citation q{quotes:"\"""\"""'""'"}.mw-parser-output .citation:target{background-color:rgba(0,127,255,0.133)}.mw-parser-output .id-lock-free.id-lock-free a{background:url("//upload.wikimedia.org/wikipedia/commons/6/65/Lock-green.svg")right 0.1em center/9px no-repeat}.mw-parser-output .id-lock-limited.id-lock-limited a,.mw-parser-output .id-lock-registration.id-lock-registration a{background:url("//upload.wikimedia.org/wikipedia/commons/d/d6/Lock-gray-alt-2.svg")right 0.1em center/9px no-repeat}.mw-parser-output .id-lock-subscription.id-lock-subscription a{background:url("//upload.wikimedia.org/wikipedia/commons/a/aa/Lock-red-alt-2.svg")right 0.1em center/9px no-repeat}.mw-parser-output .cs1-ws-icon a{background:url("//upload.wikimedia.org/wikipedia/commons/4/4c/Wikisource-logo.svg")right 0.1em center/12px no-repeat}body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-free a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-limited a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-registration a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-subscription a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .cs1-ws-icon a{background-size:contain;padding:0 1em 0 0}.mw-parser-output .cs1-code{color:inherit;background:inherit;border:none;padding:inherit}.mw-parser-output .cs1-hidden-error{display:none;color:var(--color-error,#d33)}.mw-parser-output .cs1-visible-error{color:var(--color-error,#d33)}.mw-parser-output .cs1-maint{display:none;color:#085;margin-left:0.3em}.mw-parser-output .cs1-kern-left{padding-left:0.2em}.mw-parser-output .cs1-kern-right{padding-right:0.2em}.mw-parser-output .citation .mw-selflink{font-weight:inherit}@media screen{.mw-parser-output .cs1-format{font-size:95%}html.skin-theme-clientpref-night .mw-parser-output .cs1-maint{color:#18911f}}@media screen and (prefers-color-scheme:dark){html.skin-theme-clientpref-os .mw-parser-output .cs1-maint{color:#18911f}}</style><cite class="citation book cs1"><i>The Bosch book of the Motor Car, Its evolution and engineering development</i>. St. Martin's Press. 1975. pp. <span class="nowrap">206–</span>207. <a href="/wiki/LCCN_(identifier)" class="mw-redirect" title="LCCN (identifier)">LCCN</a> <a rel="nofollow" class="external text" href="https://lccn.loc.gov/75-39516">75-39516</a>. <a href="/wiki/OCLC_(identifier)" class="mw-redirect" title="OCLC (identifier)">OCLC</a> <a rel="nofollow" class="external text" href="https://search.worldcat.org/oclc/2175044">2175044</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=The+Bosch+book+of+the+Motor+Car%2C+Its+evolution+and+engineering+development&rft.pages=%3Cspan+class%3D%22nowrap%22%3E206-%3C%2Fspan%3E207&rft.pub=St.+Martin%27s+Press&rft.date=1975&rft_id=info%3Aoclcnum%2F2175044&rft_id=info%3Alccn%2F75-39516&rfr_id=info%3Asid%2Fen.wikipedia.org%3ASpark+plug" class="Z3988"></span></span> </li> <li id="cite_note-2"><span class="mw-cite-backlink"><b><a href="#cite_ref-2">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFLaganaLimaJustoArruda2018" class="citation journal cs1">Lagana, A. A. M.; Lima, L. L.; Justo, J. F.; Arruda, B. A.; Santos, M. M. D. (2018). "Identification of combustion and detonation in spark ignition engines using ion current signal". <i>Fuel</i>. <b>227</b>: 469-477. <a href="/wiki/Bibcode_(identifier)" class="mw-redirect" title="Bibcode (identifier)">Bibcode</a>:<a rel="nofollow" class="external text" href="https://ui.adsabs.harvard.edu/abs/2018Fuel..227..469L">2018Fuel..227..469L</a>. <a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1016%2Fj.fuel.2018.04.080">10.1016/j.fuel.2018.04.080</a>. <a href="/wiki/S2CID_(identifier)" class="mw-redirect" title="S2CID (identifier)">S2CID</a> <a rel="nofollow" class="external text" href="https://api.semanticscholar.org/CorpusID:104060623">104060623</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=Fuel&rft.atitle=Identification+of+combustion+and+detonation+in+spark+ignition+engines+using+ion+current+signal&rft.volume=227&rft.pages=469-477&rft.date=2018&rft_id=https%3A%2F%2Fapi.semanticscholar.org%2FCorpusID%3A104060623%23id-name%3DS2CID&rft_id=info%3Adoi%2F10.1016%2Fj.fuel.2018.04.080&rft_id=info%3Abibcode%2F2018Fuel..227..469L&rft.aulast=Lagana&rft.aufirst=A.+A.+M.&rft.au=Lima%2C+L.+L.&rft.au=Justo%2C+J.+F.&rft.au=Arruda%2C+B.+A.&rft.au=Santos%2C+M.+M.+D.&rfr_id=info%3Asid%2Fen.wikipedia.org%3ASpark+plug" class="Z3988"></span></span> </li> <li id="cite_note-3"><span class="mw-cite-backlink"><b><a href="#cite_ref-3">^</a></b></span> <span class="reference-text"> Compare: <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFDenton2013" class="citation book cs1">Denton, Tom (2013). "Development of the automobile electrical system". <a rel="nofollow" class="external text" href="https://books.google.com/books?id=X3l0MMSMoXUC"><i>Automobile Electrical and Electronic Systems</i></a> (revised ed.). Routledge. p. 6. <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/9781136073823" title="Special:BookSources/9781136073823"><bdi>9781136073823</bdi></a><span class="reference-accessdate">. Retrieved <span class="nowrap">2018-08-20</span></span>. <q>1860[:] Lenoir produced the first spark-plug.</q></cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=bookitem&rft.atitle=Development+of+the+automobile+electrical+system&rft.btitle=Automobile+Electrical+and+Electronic+Systems&rft.pages=6&rft.edition=revised&rft.pub=Routledge&rft.date=2013&rft.isbn=9781136073823&rft.aulast=Denton&rft.aufirst=Tom&rft_id=https%3A%2F%2Fbooks.google.com%2Fbooks%3Fid%3DX3l0MMSMoXUC&rfr_id=info%3Asid%2Fen.wikipedia.org%3ASpark+plug" class="Z3988"></span></span> </li> <li id="cite_note-4"><span class="mw-cite-backlink"><b><a href="#cite_ref-4">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFDonnelly2006" class="citation web cs1">Donnelly, Jim (January 2006). <a rel="nofollow" class="external text" href="https://www.hemmings.com/magazine/hcc/2006/01/Albert-Champion/1281809.html">"Albert Champion"</a>. <i><a href="/wiki/Hemmings_Motor_News" title="Hemmings Motor News">Hemmings</a></i><span class="reference-accessdate">. Retrieved <span class="nowrap">February 6,</span> 2019</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=unknown&rft.jtitle=Hemmings&rft.atitle=Albert+Champion&rft.date=2006-01&rft.aulast=Donnelly&rft.aufirst=Jim&rft_id=https%3A%2F%2Fwww.hemmings.com%2Fmagazine%2Fhcc%2F2006%2F01%2FAlbert-Champion%2F1281809.html&rfr_id=info%3Asid%2Fen.wikipedia.org%3ASpark+plug" class="Z3988"></span></span> </li> <li id="cite_note-5"><span class="mw-cite-backlink"><b><a href="#cite_ref-5">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="http://www.asecc.com/data/plughistory.html">"A.S.E.C.C.'s History of Spark Plugs"</a>. Asecc.com. 1927-10-27<span class="reference-accessdate">. Retrieved <span class="nowrap">2011-09-17</span></span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=A.S.E.C.C.%27s+History+of+Spark+Plugs&rft.pub=Asecc.com&rft.date=1927-10-27&rft_id=http%3A%2F%2Fwww.asecc.com%2Fdata%2Fplughistory.html&rfr_id=info%3Asid%2Fen.wikipedia.org%3ASpark+plug" class="Z3988"></span></span> </li> <li id="cite_note-6"><span class="mw-cite-backlink"><b><a href="#cite_ref-6">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="http://www.gracesguide.co.uk/wiki/Lodge_Plugs">"Lodge Plugs"</a>. Gracesguide.co.uk. 2011-08-30<span class="reference-accessdate">. Retrieved <span class="nowrap">2011-09-17</span></span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=Lodge+Plugs&rft.pub=Gracesguide.co.uk&rft.date=2011-08-30&rft_id=http%3A%2F%2Fwww.gracesguide.co.uk%2Fwiki%2FLodge_Plugs&rfr_id=info%3Asid%2Fen.wikipedia.org%3ASpark+plug" class="Z3988"></span></span> </li> <li id="cite_note-7"><span class="mw-cite-backlink"><b><a href="#cite_ref-7">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://www.fhwa.dot.gov/wit/auto.htm">"Women in Transportation - Automobile Inventions"</a>. <i><a href="/wiki/Federal_Highway_Administration" title="Federal Highway Administration">Federal Highway Administration (FHWA)</a></i>. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20160623204759/http://wwwcf.fhwa.dot.gov/wit/auto.htm">Archived</a> from the original on 2016-06-23.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=unknown&rft.jtitle=Federal+Highway+Administration+%28FHWA%29&rft.atitle=Women+in+Transportation+-+Automobile+Inventions&rft_id=https%3A%2F%2Fwww.fhwa.dot.gov%2Fwit%2Fauto.htm&rfr_id=info%3Asid%2Fen.wikipedia.org%3ASpark+plug" class="Z3988"></span></span> </li> <li id="cite_note-8"><span class="mw-cite-backlink"><b><a href="#cite_ref-8">^</a></b></span> <span class="reference-text">2015 Champion Master Spark Plug Applications Catalog, p. VI</span> </li> <li id="cite_note-9"><span class="mw-cite-backlink"><b><a href="#cite_ref-9">^</a></b></span> <span class="reference-text">Notice the back inside page of the 2015-2016 Champion catalog from Europe.</span> </li> <li id="cite_note-10"><span class="mw-cite-backlink"><b><a href="#cite_ref-10">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="http://www.globaldenso.com/en/products/aftermarket/plug/basic_knowledge/construction/index.html">"Denso's "Basic Knowledge" page"</a>. Globaldenso.com<span class="reference-accessdate">. Retrieved <span class="nowrap">2011-09-17</span></span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=Denso%27s+%22Basic+Knowledge%22+page&rft.pub=Globaldenso.com&rft_id=http%3A%2F%2Fwww.globaldenso.com%2Fen%2Fproducts%2Faftermarket%2Fplug%2Fbasic_knowledge%2Fconstruction%2Findex.html&rfr_id=info%3Asid%2Fen.wikipedia.org%3ASpark+plug" class="Z3988"></span></span> </li> <li id="cite_note-11"><span class="mw-cite-backlink"><b><a href="#cite_ref-11">^</a></b></span> <span class="reference-text">The Bosch Automotive Handbook, 8th Edition, Bentley Publishers, copyright May 2011, <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/978-0-8376-1686-5" title="Special:BookSources/978-0-8376-1686-5">978-0-8376-1686-5</a>, pp 581–585.</span> </li> <li id="cite_note-Banks-12"><span class="mw-cite-backlink"><b><a href="#cite_ref-Banks_12-0">^</a></b></span> <span class="reference-text"> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFAir_Commodore_F._R._Banks1978" class="citation book cs1">Air Commodore F. R. Banks (1978). <i>I Kept No Diary</i>. Airlife. p. 113. <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/0-9504543-9-7" title="Special:BookSources/0-9504543-9-7"><bdi>0-9504543-9-7</bdi></a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=I+Kept+No+Diary&rft.pages=113&rft.pub=Airlife&rft.date=1978&rft.isbn=0-9504543-9-7&rft.au=Air+Commodore+F.+R.+Banks&rfr_id=info%3Asid%2Fen.wikipedia.org%3ASpark+plug" class="Z3988"></span></span> </li> <li id="cite_note-13"><span class="mw-cite-backlink"><b><a href="#cite_ref-13">^</a></b></span> <span class="reference-text">For examples, see the listing in the plug type chart of the 2015 Champion master spark plug application catalog, pp. VI</span> </li> <li id="cite_note-14"><span class="mw-cite-backlink"><b><a href="#cite_ref-14">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="http://marineenginedigest.com/diy/sparkplugsavvy.htm">"Marine Spark Plug Savvy"</a>. MarineEngineDigest.com. 29 April 2012<span class="reference-accessdate">. Retrieved <span class="nowrap">1 December</span> 2012</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=Marine+Spark+Plug+Savvy&rft.pub=MarineEngineDigest.com&rft.date=2012-04-29&rft_id=http%3A%2F%2Fmarineenginedigest.com%2Fdiy%2Fsparkplugsavvy.htm&rfr_id=info%3Asid%2Fen.wikipedia.org%3ASpark+plug" class="Z3988"></span></span> </li> <li id="cite_note-Hillier,_Spark_plug-15"><span class="mw-cite-backlink"><b><a href="#cite_ref-Hillier,_Spark_plug_15-0">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFHillier1991" class="citation book cs1">V.A.W., Hillier (1991). "74: The ignition system". <i>Fundamentals of Motor Vehicle Technology</i> (4th ed.). Stanley Thornes. p. 450. <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/0-7487-05317" title="Special:BookSources/0-7487-05317"><bdi>0-7487-05317</bdi></a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=bookitem&rft.atitle=74%3A+The+ignition+system&rft.btitle=Fundamentals+of+Motor+Vehicle+Technology&rft.pages=450&rft.edition=4th&rft.pub=Stanley+Thornes&rft.date=1991&rft.isbn=0-7487-05317&rft.aulast=V.A.W.&rft.aufirst=Hillier&rfr_id=info%3Asid%2Fen.wikipedia.org%3ASpark+plug" class="Z3988"></span></span> </li> <li id="cite_note-ih-16"><span class="mw-cite-backlink">^ <a href="#cite_ref-ih_16-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-ih_16-1"><sup><i><b>b</b></i></sup></a> <a href="#cite_ref-ih_16-2"><sup><i><b>c</b></i></sup></a></span> <span class="reference-text">International Harvester, <a rel="nofollow" class="external text" href="http://www.liberatedmanuals.com/TM-5-4210-230-14-and-P-1.pdf">Truck Service Manual TM 5-4210-230-14&P-1</a> - Electrical - Ignition Coils and Condensers, CTS-2013-E p. 5 (PDF page 545)</span> </li> <li id="cite_note-wastedspark-17"><span class="mw-cite-backlink"><b><a href="#cite_ref-wastedspark_17-0">^</a></b></span> <span class="reference-text">NGK, <a rel="nofollow" class="external text" href="https://www.ngk.com/glossary/8/spark-plug/W">Wasted Spark Ignition</a></span> </li> <li id="cite_note-18"><span class="mw-cite-backlink"><b><a href="#cite_ref-18">^</a></b></span> <span class="reference-text">See p. 824 of the 2015 Champion Master Catalog. <a rel="nofollow" class="external free" href="http://www.fme-cat.com/catalogs.aspx">http://www.fme-cat.com/catalogs.aspx</a> <a rel="nofollow" class="external text" href="https://web.archive.org/web/20180601144828/http://fme-cat.com/catalogs.aspx">Archived</a> 2018-06-01 at the <a href="/wiki/Wayback_Machine" title="Wayback Machine">Wayback Machine</a></span> </li> <li id="cite_note-19"><span class="mw-cite-backlink"><b><a href="#cite_ref-19">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://www.orau.org/health-physics-museum/collection/consumer/miscellaneous/spark-plugs.html">"Radioactive spark plugs"</a>. Oak Ridge Associated Universities. January 20, 1999<span class="reference-accessdate">. Retrieved <span class="nowrap">October 7,</span> 2021</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=Radioactive+spark+plugs&rft.pub=Oak+Ridge+Associated+Universities&rft.date=1999-01-20&rft_id=https%3A%2F%2Fwww.orau.org%2Fhealth-physics-museum%2Fcollection%2Fconsumer%2Fmiscellaneous%2Fspark-plugs.html&rfr_id=info%3Asid%2Fen.wikipedia.org%3ASpark+plug" class="Z3988"></span></span> </li> <li id="cite_note-20"><span class="mw-cite-backlink"><b><a href="#cite_ref-20">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFPittman2017" class="citation web cs1">Pittman, Cassandra (February 3, 2017). <a rel="nofollow" class="external text" href="http://www.utoledo.edu/nsm/ic/elements/polonium.html">"Polonium"</a>. <i>The Instrumentation Center</i>. University of Toledo<span class="reference-accessdate">. Retrieved <span class="nowrap">August 23,</span> 2018</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=unknown&rft.jtitle=The+Instrumentation+Center&rft.atitle=Polonium&rft.date=2017-02-03&rft.aulast=Pittman&rft.aufirst=Cassandra&rft_id=http%3A%2F%2Fwww.utoledo.edu%2Fnsm%2Fic%2Felements%2Fpolonium.html&rfr_id=info%3Asid%2Fen.wikipedia.org%3ASpark+plug" class="Z3988"></span></span> </li> <li id="cite_note-21"><span class="mw-cite-backlink"><b><a href="#cite_ref-21">^</a></b></span> <span class="reference-text">For example, notice the 2015-2016 Champion master catalog from Europe's type chart, which flips out from the back. In many cases, depending on the design, "platinum" is listed as the metal type.</span> </li> <li id="cite_note-22"><span class="mw-cite-backlink"><b><a href="#cite_ref-22">^</a></b></span> <span class="reference-text">For example, in the 1967 Champion spark plug catalog, the "Deluxe Gap Tool & Gauges" on p. 38 is designed to handle gaps from 0.38 to 1.02 mm (0.015 to 0.040 in), which is less than the gap required by many modern cars. As for older cars before c. 1960, notice the vintage vehicle section of the 1997 AC Delco Spark Plug Catalog, page 250 to 264. Gaps in the 1920s for many makes were often 0.64 mm (0.025 in). However, many modern cars have gaps not much larger, such as those made by Volvo from 1967 to 2014 normally had gaps of 0.71 to 0.76 mm (0.028 to 0.030 in). See this make's listings in the 2015 Champion Master Spark Plug Application Catalog, pp. 333 to 339, for which the only exception were some 4.4 liter engines.</span> </li> <li id="cite_note-23"><span class="mw-cite-backlink"><b><a href="#cite_ref-23">^</a></b></span> <span class="reference-text">For example, the Ford Crown Victoria's 4.6 liter engine required a 1.1 mm (0.044 in) gap when using CNG, but requires a 1.4 mm (0.054 in) gap when using gas. See the 2015 Champion Master Spark Plug Application Catalog, p. 124; a technical explanation is found on p. 825.</span> </li> <li id="cite_note-24"><span class="mw-cite-backlink"><b><a href="#cite_ref-24">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://vinsonar.com/help/spark-plug-guide/">"How to Choose Proper Spark Plugs for Your Engine"</a>. <i>VIN Sonar | help - Automotive Guides and Online Tools</i>. 2022-01-27<span class="reference-accessdate">. Retrieved <span class="nowrap">2022-05-12</span></span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=unknown&rft.jtitle=VIN+Sonar+%7C+help+-+Automotive+Guides+and+Online+Tools&rft.atitle=How+to+Choose+Proper+Spark+Plugs+for+Your+Engine&rft.date=2022-01-27&rft_id=https%3A%2F%2Fvinsonar.com%2Fhelp%2Fspark-plug-guide%2F&rfr_id=info%3Asid%2Fen.wikipedia.org%3ASpark+plug" class="Z3988"></span></span> </li> <li id="cite_note-25"><span class="mw-cite-backlink"><b><a href="#cite_ref-25">^</a></b></span> <span class="reference-text">For example, notice the torque recommendations on p. 823 of the 2015 Champion Master Spark Plug Application Catalog.</span> </li> </ol></div></div> <div class="mw-heading mw-heading2"><h2 id="External_links">External links</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Spark_plug&action=edit&section=23" title="Edit section: External 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src="//upload.wikimedia.org/wikipedia/commons/thumb/d/df/Wikibooks-logo-en-noslogan.svg/40px-Wikibooks-logo-en-noslogan.svg.png" decoding="async" width="40" height="40" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/d/df/Wikibooks-logo-en-noslogan.svg/60px-Wikibooks-logo-en-noslogan.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/d/df/Wikibooks-logo-en-noslogan.svg/80px-Wikibooks-logo-en-noslogan.svg.png 2x" data-file-width="400" data-file-height="400" /></a></span></div> <div class="side-box-text plainlist">Wikibooks has a book on the topic of: <i><b><a href="https://en.wikibooks.org/wiki/Automobile_Repair/Spark_plugs" class="extiw" title="wikibooks:Automobile Repair/Spark plugs">Automobile Repair/Spark plugs</a></b></i></div></div> </div> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1235681985"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1237033735"><div class="side-box side-box-right 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engine">Internal combustion engine</a></div></th></tr><tr><td class="navbox-abovebelow" colspan="2"><div><i>Part of the <a href="/wiki/Car" title="Car">Automobile</a> series</i></div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Engine_block" title="Engine block">Engine block</a> and<br /> rotating assembly</th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Balance_shaft" title="Balance shaft">Balance shaft</a></li> <li><a href="/wiki/Block_heater" title="Block heater">Block heater</a></li> <li><a href="/wiki/Bore_(engine)" title="Bore (engine)">Bore</a></li> <li><a href="/wiki/Connecting_rod" title="Connecting rod">Connecting rod</a></li> <li><a href="/wiki/Crankcase" title="Crankcase">Crankcase</a></li> <li><a href="/wiki/Crankcase_ventilation_system" title="Crankcase ventilation system">Crankcase ventilation system (PCV valve)</a></li> <li><a href="/wiki/Crankpin" title="Crankpin">Crankpin</a></li> <li><a href="/wiki/Crankshaft" title="Crankshaft">Crankshaft</a></li> <li><a href="/wiki/Core_plug" title="Core plug">Core plug (freeze plug)</a></li> <li><a href="/wiki/Cylinder_(engine)" title="Cylinder (engine)">Cylinder</a> (<a href="/wiki/Cylinder_bank" class="mw-redirect" title="Cylinder bank">bank</a>, <a href="/wiki/Engine_configuration" title="Engine configuration">layout</a>)</li> <li><a href="/wiki/Engine_displacement" title="Engine displacement">Displacement</a></li> <li><a href="/wiki/Flywheel" title="Flywheel">Flywheel</a></li> <li><a href="/wiki/Firing_order" title="Firing order">Firing order</a></li> <li><a href="/wiki/Stroke_(engine)" title="Stroke (engine)">Stroke</a></li> <li><a href="/wiki/Main_bearing" title="Main bearing">Main bearing</a></li> <li><a href="/wiki/Piston" title="Piston">Piston</a></li> <li><a href="/wiki/Piston_ring" title="Piston ring">Piston ring</a></li> <li><a href="/wiki/Starter_ring_gear" title="Starter ring gear">Starter ring gear</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Valvetrain" title="Valvetrain">Valvetrain</a> and<br /> <a href="/wiki/Cylinder_head" title="Cylinder head">Cylinder head</a></th><td class="navbox-list-with-group navbox-list navbox-even hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Flathead_engine" title="Flathead engine">Flathead layout</a></li> <li><a href="/wiki/Overhead_camshaft_engine" title="Overhead camshaft engine">Overhead camshaft layout</a></li> <li><a href="/wiki/Overhead_valve_engine" title="Overhead valve engine">Overhead valve (pushrod) layout</a></li></ul> <ul><li><a href="/wiki/Tappet" title="Tappet">Tappet / lifter</a></li> <li><a href="/wiki/Camshaft" title="Camshaft">Camshaft</a></li> <li><a href="/wiki/Chest_(mechanical_engineering)" title="Chest (mechanical engineering)">Chest</a></li> <li><a href="/wiki/Combustion_chamber" title="Combustion chamber">Combustion chamber</a></li> <li><a href="/wiki/Compression_ratio" title="Compression ratio">Compression ratio</a></li> <li><a href="/wiki/Head_gasket" title="Head gasket">Head gasket</a></li> <li><a href="/wiki/Rocker_arm" title="Rocker arm">Rocker arm</a></li> <li><a href="/wiki/Timing_belt_(camshaft)" title="Timing belt (camshaft)">Timing belt</a></li> <li><a href="/wiki/Poppet_valve" title="Poppet valve">Valve</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Forced_induction" title="Forced induction">Forced induction</a></th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Blowoff_valve" title="Blowoff valve">Blowoff valve</a></li> <li><a href="/wiki/Boost_controller" title="Boost controller">Boost controller</a></li> <li><a href="/wiki/Intercooler" title="Intercooler">Intercooler</a></li> <li><a href="/wiki/Supercharger" title="Supercharger">Supercharger</a></li> <li><a href="/wiki/Turbocharger" title="Turbocharger">Turbocharger</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Fuel system</th><td class="navbox-list-with-group navbox-list navbox-even hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Diesel_engine" title="Diesel engine">Diesel engine</a></li> <li><a href="/wiki/Petrol_engine" title="Petrol engine">Petrol engine</a></li> <li><a href="/wiki/Carburetor" title="Carburetor">Carburetor</a></li> <li><a href="/wiki/Fuel_filter" title="Fuel filter">Fuel filter</a></li> <li><a href="/wiki/Fuel_injection" title="Fuel injection">Fuel injection</a></li> <li><a href="/wiki/Fuel_pump" title="Fuel pump">Fuel pump</a></li> <li><a href="/wiki/Fuel_tank" title="Fuel tank">Fuel tank</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Ignition_system" title="Ignition system">Ignition</a></th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Ignition_magneto" title="Ignition magneto">Magneto</a></li> <li><a href="/wiki/Compression_ignition" class="mw-redirect" title="Compression ignition">Compression ignition</a></li> <li><a href="/wiki/Coil-on-plug_ignition" class="mw-redirect" title="Coil-on-plug ignition">Coil-on-plug</a></li> <li><a href="/wiki/Distributor" title="Distributor">Distributor</a></li> <li><a href="/wiki/Glow_plug_(diesel_engine)" class="mw-redirect" title="Glow plug (diesel engine)">Glow plug</a></li> <li><a href="/wiki/Ignition_coil" title="Ignition coil">Ignition coil</a></li> <li><a class="mw-selflink selflink">Spark plug</a></li> <li><a href="/wiki/Spark_plug_wires" title="Spark plug wires">Spark plug wires</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><div style="display: inline-block; line-height: 1.2em; padding: .1em 0;">Engine management</div></th><td class="navbox-list-with-group navbox-list navbox-even hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Engine_control_unit" title="Engine control unit">Engine control unit (ECU)</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><div style="display: inline-block; line-height: 1.2em; padding: .1em 0;">Electrical system</div></th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Alternator_(automotive)" title="Alternator (automotive)">Alternator</a></li> <li><a href="/wiki/Automotive_battery" title="Automotive battery">Battery</a></li> <li><a href="/wiki/Dynamo" title="Dynamo">Dynamo</a></li> <li><a href="/wiki/Starter_(engine)" title="Starter (engine)">Starter motor</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Intake system</th><td class="navbox-list-with-group navbox-list navbox-even hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Airbox" title="Airbox">Airbox</a></li> <li><a href="/wiki/Air_filter#Internal_combustion_engine_air_filters" title="Air filter">Air filter</a></li> <li><a href="/wiki/Idle_air_control_actuator" title="Idle air control actuator">Idle air control actuator</a></li> <li><a href="/wiki/Inlet_manifold" title="Inlet manifold">Inlet manifold</a></li> <li><a href="/wiki/MAP_sensor" title="MAP sensor">MAP sensor</a></li> <li><a href="/wiki/Mass_flow_sensor" title="Mass flow sensor">MAF sensor</a></li> <li><a href="/wiki/Throttle" title="Throttle">Throttle</a></li> <li><a href="/wiki/Throttle_position_sensor" title="Throttle position sensor">Throttle position sensor</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Exhaust_system" title="Exhaust system">Exhaust system</a></th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Catalytic_converter" title="Catalytic converter">Catalytic converter</a></li> <li><a href="/wiki/Diesel_particulate_filter" title="Diesel particulate filter">Diesel particulate filter</a></li> <li><a href="/wiki/Exhaust_gas_temperature_gauge" title="Exhaust gas temperature gauge">EGT sensor</a></li> <li><a href="/wiki/Exhaust_manifold" title="Exhaust manifold">Exhaust manifold</a></li> <li><a href="/wiki/Muffler" title="Muffler">Muffler</a></li> <li><a href="/wiki/Oxygen_sensor#Automotive_applications" title="Oxygen sensor">Oxygen sensor</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Internal_combustion_engine_cooling" title="Internal combustion engine cooling">Cooling system</a></th><td class="navbox-list-with-group navbox-list navbox-even hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Air_cooling" title="Air cooling">Air cooling</a></li> <li><a href="/wiki/Water_cooling" title="Water cooling">Water cooling</a></li></ul> <ul><li><a href="/wiki/Fan_(machine)" title="Fan (machine)">Electric fan</a></li> <li><a href="/wiki/Radiator_(engine_cooling)" title="Radiator (engine cooling)">Radiator</a></li> <li><a href="/wiki/Thermostat" title="Thermostat">Thermostat</a></li> <li><a href="/wiki/Fan_clutch" title="Fan clutch">Viscous fan (fan clutch)</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Lubrication</th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Motor_oil" title="Motor oil">Oil</a></li> <li><a href="/wiki/Oil_filter" title="Oil filter">Oil filter</a></li> <li><a href="/wiki/Oil_pump_(internal_combustion_engine)" title="Oil pump (internal combustion engine)">Oil pump</a></li> <li><a href="/wiki/Sump" title="Sump">Sump</a> (<a href="/wiki/Wet_sump" title="Wet sump">Wet sump</a>, <a href="/wiki/Dry_sump" title="Dry sump">Dry sump</a>)</li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Other</th><td class="navbox-list-with-group navbox-list navbox-even hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Engine_knocking" title="Engine knocking">Knocking / pinging</a></li> <li><a href="/wiki/Power_band" title="Power band">Power band</a></li> <li><a href="/wiki/Redline" title="Redline">Redline</a></li> <li><a href="/wiki/Stratified_charge_engine" title="Stratified charge engine">Stratified charge</a></li> <li><a href="/wiki/Dead_centre_(engineering)" title="Dead centre (engineering)">Top dead centre</a></li></ul> </div></td></tr><tr><td class="navbox-abovebelow hlist" colspan="2" style="font-weight:bold;"><div> <ul><li><a href="/wiki/Portal:Cars" title="Portal:Cars">Portal</a></li> <li><a href="/wiki/Category:Cars" title="Category:Cars">Category</a></li></ul> </div></td></tr></tbody></table></div> <div class="navbox-styles"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1129693374"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1236075235"></div><div role="navigation" class="navbox" aria-labelledby="Aircraft_piston_engine_components,_systems_and_terminology309" style="padding:3px"><table class="nowraplinks mw-collapsible mw-collapsed navbox-inner" style="border-spacing:0;background:transparent;color:inherit"><tbody><tr><th scope="col" class="navbox-title" colspan="2"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1129693374"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1239400231"><div class="navbar plainlinks hlist navbar-mini"><ul><li class="nv-view"><a href="/wiki/Template:Aircraft_piston_engine_components" title="Template:Aircraft piston engine components"><abbr title="View this template">v</abbr></a></li><li class="nv-talk"><a href="/wiki/Template_talk:Aircraft_piston_engine_components" title="Template talk:Aircraft piston engine components"><abbr title="Discuss this template">t</abbr></a></li><li class="nv-edit"><a href="/wiki/Special:EditPage/Template:Aircraft_piston_engine_components" title="Special:EditPage/Template:Aircraft piston engine components"><abbr title="Edit this template">e</abbr></a></li></ul></div><div id="Aircraft_piston_engine_components,_systems_and_terminology309" style="font-size:114%;margin:0 4em"><a href="/wiki/Aircraft_engine" title="Aircraft engine">Aircraft</a> <a href="/wiki/Reciprocating_engine" title="Reciprocating engine">piston engine</a> components, systems and terminology</div></th></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Reciprocating_engine" title="Reciprocating engine">Piston engines</a></th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"></div><table class="nowraplinks navbox-subgroup" style="border-spacing:0"><tbody><tr><th scope="row" class="navbox-group" style="width:1%">Mechanical<br />components</th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Camshaft" title="Camshaft">Camshaft</a></li> <li><a href="/wiki/Connecting_rod" title="Connecting rod">Connecting rod</a></li> <li><a href="/wiki/Crankpin" title="Crankpin">Crankpin</a></li> <li><a href="/wiki/Crankshaft" title="Crankshaft">Crankshaft</a></li> <li><a href="/wiki/Cylinder_(engine)" title="Cylinder (engine)">Cylinder</a></li> <li><a href="/wiki/Cylinder_head" title="Cylinder head">Cylinder head</a></li> <li><a href="/wiki/Gudgeon_pin" title="Gudgeon pin">Gudgeon pin</a></li> <li><a href="/wiki/Hydraulic_tappet" title="Hydraulic tappet">Hydraulic tappet</a></li> <li><a href="/wiki/Main_bearing" title="Main bearing">Main bearing</a></li> <li><a href="/wiki/Obturator_ring" title="Obturator ring">Obturator ring</a></li> <li><a href="/wiki/Oil_pump_(internal_combustion_engine)" title="Oil pump (internal combustion engine)">Oil pump</a></li> <li><a href="/wiki/Piston" title="Piston">Piston</a></li> <li><a href="/wiki/Piston_ring" title="Piston ring">Piston ring</a></li> <li><a href="/wiki/Poppet_valve" title="Poppet valve">Poppet valve</a></li> <li><a href="/wiki/Overhead_valve_engine" title="Overhead valve engine">Pushrod</a></li> <li><a href="/wiki/Rocker_arm" title="Rocker arm">Rocker arm</a></li> <li><a href="/wiki/Sleeve_valve" title="Sleeve valve">Sleeve valve</a></li> <li><a href="/wiki/Tappet" title="Tappet">Tappet</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Electrical<br />components</th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Alternator_(automotive)" title="Alternator (automotive)">Alternator</a></li> <li><a href="/wiki/Capacitor_discharge_ignition" title="Capacitor discharge ignition">Capacitor discharge ignition</a></li> <li><a href="/wiki/Dual_ignition" title="Dual ignition">Dual ignition</a></li> <li><a href="/wiki/Fuel_injection" title="Fuel injection">Electronic fuel injection</a></li> <li><a href="/wiki/Electric_generator" title="Electric generator">Generator</a></li> <li><a href="/wiki/Ignition_system" title="Ignition system">Ignition system</a></li> <li><a href="/wiki/Ignition_magneto" title="Ignition magneto">Magneto</a></li> <li><a class="mw-selflink selflink">Spark plug</a></li> <li><a href="/wiki/Starter_(engine)" title="Starter (engine)">Starter</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Terminology</th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Air-cooled_engine" title="Air-cooled engine">Air-cooled</a></li> <li><a href="/wiki/Aircraft_engine_starting" title="Aircraft engine starting">Aircraft engine starting</a></li> <li><a href="/wiki/Bore_(engine)" title="Bore (engine)">Bore</a></li> <li><a href="/wiki/Compression_ratio" title="Compression ratio">Compression ratio</a></li> <li><a href="/wiki/Dead_centre_(engineering)" title="Dead centre (engineering)">Dead centre</a></li> <li><a href="/wiki/Engine_displacement" title="Engine displacement">Engine displacement</a></li> <li><a href="/wiki/Four-stroke_engine" title="Four-stroke engine">Four-stroke engine</a></li> <li><a href="/wiki/Horsepower" title="Horsepower">Horsepower</a></li> <li><a href="/wiki/Ignition_timing" title="Ignition timing">Ignition timing</a></li> <li><a href="/wiki/Manifold_vacuum" title="Manifold vacuum">Manifold pressure</a></li> <li><a href="/wiki/Mean_effective_pressure" title="Mean effective pressure">Mean effective pressure</a></li> <li><a href="/wiki/Naturally_aspirated_engine" title="Naturally aspirated engine">Naturally aspirated</a></li> <li><a href="/wiki/Gnome_Monosoupape" title="Gnome Monosoupape">Monosoupape</a></li> <li><a href="/wiki/Overhead_camshaft" class="mw-redirect" title="Overhead camshaft">Overhead camshaft</a></li> <li><a href="/wiki/Overhead_valve_engine" title="Overhead valve engine">Overhead valve engine</a></li> <li><a href="/wiki/Rotary_engine" title="Rotary engine">Rotary engine</a></li> <li><a href="/wiki/Shock_cooling" title="Shock cooling">Shock cooling</a></li> <li><a href="/wiki/Stroke_(engine)" title="Stroke (engine)">Stroke</a></li> <li><a href="/wiki/Time_between_overhauls" title="Time between overhauls">Time between overhauls</a></li> <li><a href="/wiki/Two-stroke_engine" title="Two-stroke engine">Two-stroke engine</a></li> <li><a href="/wiki/Valve_timing" title="Valve timing">Valve timing</a></li> <li><a href="/wiki/Volumetric_efficiency" title="Volumetric efficiency">Volumetric efficiency</a></li></ul> </div></td></tr></tbody></table><div></div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Propeller_(aeronautics)" title="Propeller (aeronautics)">Propellers</a></th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"></div><table class="nowraplinks navbox-subgroup" style="border-spacing:0"><tbody><tr><th scope="row" class="navbox-group" style="width:1%">Components</th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Propeller_governor" class="mw-redirect" title="Propeller governor">Propeller governor</a></li> <li><a href="/wiki/Propeller_speed_reduction_unit" title="Propeller speed reduction unit">Propeller speed reduction unit</a></li> <li><a href="/wiki/Spinner_(aeronautics)" title="Spinner (aeronautics)">Spinner</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Terminology</th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Autofeather" title="Autofeather">Autofeather</a></li> <li><a href="/wiki/Blade_pitch" title="Blade pitch">Blade pitch</a></li> <li><a href="/wiki/Constant-speed_propeller" class="mw-redirect" title="Constant-speed propeller">Constant-speed</a></li> <li><a href="/wiki/Contra-rotating_propellers" title="Contra-rotating propellers">Contra-rotating</a></li> <li><a href="/wiki/Counter-rotating_propellers" title="Counter-rotating propellers">Counter-rotating</a></li> <li><a href="/wiki/Scimitar_propeller" title="Scimitar propeller">Scimitar</a></li> <li><a href="/wiki/Single-blade_propeller" title="Single-blade propeller">Single-blade</a></li> <li><a href="/wiki/Variable-pitch_propeller_(aeronautics)" title="Variable-pitch propeller (aeronautics)">Variable-pitch</a></li></ul> </div></td></tr></tbody></table><div></div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Engine instruments</th><td class="navbox-list-with-group navbox-list navbox-even hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Annunciator_panel" title="Annunciator panel">Annunciator panel</a></li> <li><a href="/wiki/Electronic_flight_instrument_system" title="Electronic flight instrument system">EFIS</a></li> <li><a href="/wiki/Engine-indicating_and_crew-alerting_system" title="Engine-indicating and crew-alerting system">EICAS</a></li> <li><a href="/wiki/Flight_data_recorder" class="mw-redirect" title="Flight data recorder">Flight data recorder</a></li> <li><a href="/wiki/Glass_cockpit" title="Glass cockpit">Glass cockpit</a></li> <li><a href="/wiki/Hobbs_meter" title="Hobbs meter">Hobbs meter</a></li> <li><a href="/wiki/Tachometer" title="Tachometer">Tachometer</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Aircraft_engine_controls" title="Aircraft engine controls">Engine controls</a></th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Carburetor_heat" title="Carburetor heat">Carburetor heat</a></li> <li><a href="/wiki/Throttle" title="Throttle">Throttle</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Aircraft_fuel_system" title="Aircraft fuel system">Fuel</a> and induction<br />system</th><td class="navbox-list-with-group navbox-list navbox-even hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Avgas" title="Avgas">Avgas</a></li> <li><a href="/wiki/Carburetor" title="Carburetor">Carburetor</a></li> <li><a href="/wiki/Fuel_injection" title="Fuel injection">Fuel injection</a></li> <li><a href="/wiki/Gascolator" title="Gascolator">Gascolator</a></li> <li><a href="/wiki/Inlet_manifold" title="Inlet manifold">Inlet manifold</a></li> <li><a href="/wiki/Intercooler" title="Intercooler">Intercooler</a></li> <li><a href="/wiki/Pressure_carburetor" title="Pressure carburetor">Pressure carburetor</a></li> <li><a href="/wiki/Supercharger" title="Supercharger">Supercharger</a></li> <li><a href="/wiki/Turbocharger" title="Turbocharger">Turbocharger</a></li> <li><a href="/wiki/Updraft_carburetor" title="Updraft carburetor">Updraft carburetor</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Other systems</th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Auxiliary_power_unit" title="Auxiliary power unit">Auxiliary power unit</a></li> <li><a href="/wiki/Coffman_engine_starter" title="Coffman 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