{"title":"MerCruiser 7.4L 454 CID 420HP V-8 Sterndrive — 0A398941 THRU 0B622418 · Exhaust Manifold \/ Elbow(425 GIL System)","description":"\u003cdiv class=\"model-catalog\"\u003e\n\u003cp\u003e\u003ca href=\"\/collections\/mercruiser-7-4l-454-cid-420hp-v-8-sterndrive-0a398941-thru-0b622418\"\u003eBack to MerCruiser 7.4L 454 CID 420HP V-8 Sterndrive — 0A398941 THRU 0B622418\u003c\/a\u003e\u003c\/p\u003e\n\u003cp\u003eMatch the application and restrictions below with your engine or drive before ordering.\u003c\/p\u003e\n\u003cdiv style=\"overflow-x:auto\"\u003e\u003ctable\u003e\n\u003cthead\u003e\u003ctr\u003e\n\u003cth\u003eProduct\u003c\/th\u003e\n\u003cth\u003eApplication\u003c\/th\u003e\n\u003cth\u003eCatalog reference\u003c\/th\u003e\n\u003c\/tr\u003e\u003c\/thead\u003e\n\u003ctbody\u003e\u003ctr\u003e\n\u003ctd\u003e\u003ca href=\"\/products\/27-46820-exhaust-manifold-gasket-for-mercruiser-gm-big-block\"\u003e27-46820 Exhaust Manifold Gasket for MerCruiser GM Big Block\u003c\/a\u003e\u003c\/td\u003e\n\u003ctd\u003eSerial: 0A398941 THRU 0B622418\u003c\/td\u003e\n\u003ctd\u003e\u003cspan class=\"catalog-reference\"\u003eCatalog parts list · Ref. 21\u003c\/span\u003e\u003c\/td\u003e\n\u003c\/tr\u003e\u003c\/tbody\u003e\n\u003c\/table\u003e\u003c\/div\u003e\n\u003c\/div\u003e","products":[{"product_id":"27-46820-exhaust-manifold-gasket-for-mercruiser-gm-big-block","title":"27-46820 Exhaust Manifold Gasket for MerCruiser GM Big Block","description":"\u003cdiv style=\"width:100%;max-width:960px;margin:0 auto;box-sizing:border-box;font-family:Arial,Helvetica,sans-serif;font-size:16px;line-height:1.75;color:#293a35;background:#ffffff;overflow-wrap:anywhere;\"\u003e\n  \u003cdiv style=\"padding:28px 24px;margin:0 0 40px;border-top:5px solid #234d40;background:#f5f3ec;box-sizing:border-box;\"\u003e\n    \u003cp style=\"margin:0 0 14px;color:#456052;font-size:12px;line-height:1.6;font-weight:700;letter-spacing:1.4px;text-transform:uppercase;\"\u003eSERDAMARINE \/ MARINE EXHAUST PARTS\u003c\/p\u003e\n    \u003ch2 style=\"margin:0 0 18px;color:#203e32;font-family:Georgia,Times,serif;font-size:clamp(25px,4vw,34px);font-weight:400;line-height:1.25;\"\u003eExhaust Manifold Gasket — Adapter Plate to GM Manifold\u003c\/h2\u003e\n    \u003cp style=\"margin:0 0 14px;\"\u003eThis aftermarket exhaust manifold gasket (OEM reference 27-46820) seals the exhaust manifold joint on specified MerCruiser, Volvo Penta, and OMC Cobra GM-based big-block V8 marine engines (7.4L \/ 454 CID, 8.1L \/ 496 CID, and 8.2L \/ 502 CID). It is also used at the adapter-plate-to-GM-exhaust-manifold interface in matching two-piece Ford 460-to-GM 454 manifold conversion assemblies.\u003c\/p\u003e\n    \u003cp style=\"margin:0 0 14px;\"\u003eThis item is a single exhaust manifold gasket component, not a complete exhaust manifold assembly or a complete manifold gasket repair kit.\u003c\/p\u003e\n  \u003c\/div\u003e\n\n  \u003csection style=\"margin:0 0 40px;\"\u003e\n    \u003ch2 style=\"margin:0 0 18px;padding:0 0 10px;border-bottom:1px solid #bdc9c0;color:#234d40;font-family:Georgia,Times,serif;font-size:25px;font-weight:400;line-height:1.35;\"\u003e27-46820 Exhaust Manifold Gasket for MerCruiser GM Big Block\u003c\/h2\u003e\n\u003cp style=\"margin:0 0 14px;\"\u003eAftermarket exhaust manifold gasket referenced to MerCruiser 27-46820 for the specified GM 7.4L, 8.1L and 8.2L big-block applications. Wet-joint and dry-joint conditions remain separated below.\u003c\/p\u003e\u003c\/section\u003e\n\n  \u003csection style=\"margin:0 0 40px;\"\u003e\n    \u003ch2 style=\"margin:0 0 18px;padding:0 0 10px;border-bottom:1px solid #bdc9c0;color:#234d40;font-family:Georgia,Times,serif;font-size:25px;font-weight:400;line-height:1.35;\"\u003eEngine Applications\u003c\/h2\u003e\n\u003cul style=\"padding-left:20px;line-height:1.75;\"\u003e\n\u003cli\u003eMerCruiser MODEL 330–370, GM V8 Big Block, 454\/502 CID; Wet Joint; 1981 onward.\u003c\/li\u003e\n\u003cli\u003eMerCruiser GM V8 7.4L \/ 454 CID, 8.1L \/ 496 CID and 8.2L \/ 502 CID applications; match the individual exhaust assembly.\u003c\/li\u003e\n\u003cli\u003eMerCruiser GM V8 Big Block, Dry Joint; match the specific manifold gasket interface. The 6-inch configuration designation is not a gasket measurement.\u003c\/li\u003e\n\u003cli\u003eChevrolet \/ Chevy 454 and 502 engine-base applications with the specified marine exhaust manifold.\u003c\/li\u003e\n\u003c\/ul\u003e\u003c\/section\u003e\n\n  \u003csection style=\"margin:0 0 40px;\"\u003e\n    \u003ch2 style=\"margin:0 0 18px;padding:0 0 10px;border-bottom:1px solid #bdc9c0;color:#234d40;font-family:Georgia,Times,serif;font-size:25px;font-weight:400;line-height:1.35;\"\u003eReference Numbers\u003c\/h2\u003e\n    \u003cp style=\"margin:0 0 14px;\"\u003eThe numbers below are provided as identification references across corresponding engine and aftermarket brands. They do not independently guarantee interchangeability across different manifold designs or indicate manufacturer identity; compare the complete part number (including any prefix, leading zero, and A1 suffix) along with the physical gasket shape.\u003c\/p\u003e\n    \u003ctable style=\"width:100%;table-layout:fixed;border-collapse:collapse;text-align:left;\"\u003e\n      \u003ctbody\u003e\n        \u003ctr\u003e\n          \u003cth scope=\"row\" style=\"width:36%;padding:13px 10px 13px 0;border-bottom:1px solid #e0e5df;vertical-align:top;text-align:left;font-size:14px;font-weight:700;color:#456052;\"\u003eMerCruiser Reference\u003c\/th\u003e\n          \u003ctd style=\"padding:13px 0 13px 10px;border-bottom:1px solid #e0e5df;vertical-align:top;\"\u003e27-46820, 27-46820A1, 46820, 46820A1\u003c\/td\u003e\n        \u003c\/tr\u003e\n        \u003ctr\u003e\n          \u003cth scope=\"row\" style=\"width:36%;padding:13px 10px 13px 0;border-bottom:1px solid #e0e5df;vertical-align:top;text-align:left;font-size:14px;font-weight:700;color:#456052;\"\u003eVolvo Penta Reference\u003c\/th\u003e\n          \u003ctd style=\"padding:13px 0 13px 10px;border-bottom:1px solid #e0e5df;vertical-align:top;\"\u003e3852472\u003c\/td\u003e\n        \u003c\/tr\u003e\n        \u003ctr\u003e\n          \u003cth scope=\"row\" style=\"width:36%;padding:13px 10px 13px 0;border-bottom:1px solid #e0e5df;vertical-align:top;text-align:left;font-size:14px;font-weight:700;color:#456052;\"\u003eOMC Cobra Reference\u003c\/th\u003e\n          \u003ctd style=\"padding:13px 0 13px 10px;border-bottom:1px solid #e0e5df;vertical-align:top;\"\u003e0508878, 0778127, 0909613, 508878, 778127, 909613, 3852472\u003c\/td\u003e\n        \u003c\/tr\u003e\n        \u003ctr\u003e\n          \u003cth scope=\"row\" style=\"width:36%;padding:13px 10px 13px 0;border-bottom:1px solid #e0e5df;vertical-align:top;text-align:left;font-size:14px;font-weight:700;color:#456052;\"\u003eCrusader Reference\u003c\/th\u003e\n          \u003ctd style=\"padding:13px 0 13px 10px;border-bottom:1px solid #e0e5df;vertical-align:top;\"\u003e96653\u003c\/td\u003e\n        \u003c\/tr\u003e\n        \u003ctr\u003e\n          \u003cth scope=\"row\" style=\"width:36%;padding:13px 10px 13px 0;border-bottom:1px solid #e0e5df;vertical-align:top;text-align:left;font-size:14px;font-weight:700;color:#456052;\"\u003eSierra Reference\u003c\/th\u003e\n          \u003ctd style=\"padding:13px 0 13px 10px;border-bottom:1px solid #e0e5df;vertical-align:top;\"\u003e18-0418\u003c\/td\u003e\n        \u003c\/tr\u003e\n        \u003ctr\u003e\n          \u003cth scope=\"row\" style=\"width:36%;padding:13px 10px 13px 0;border-bottom:1px solid #e0e5df;vertical-align:top;text-align:left;font-size:14px;font-weight:700;color:#456052;\"\u003eGLM Reference\u003c\/th\u003e\n          \u003ctd style=\"padding:13px 0 13px 10px;border-bottom:1px solid #e0e5df;vertical-align:top;\"\u003e33760, 37760\u003c\/td\u003e\n        \u003c\/tr\u003e\n        \u003ctr\u003e\n          \u003cth scope=\"row\" style=\"width:36%;padding:13px 10px 13px 0;border-bottom:1px solid #e0e5df;vertical-align:top;text-align:left;font-size:14px;font-weight:700;color:#456052;\"\u003eMallory Reference\u003c\/th\u003e\n          \u003ctd style=\"padding:13px 0 13px 10px;border-bottom:1px solid #e0e5df;vertical-align:top;\"\u003e9-61400\u003c\/td\u003e\n        \u003c\/tr\u003e\n      \u003c\/tbody\u003e\n    \u003c\/table\u003e\n    \u003cdiv style=\"margin:18px 0 0;padding:14px 16px;border-left:3px solid #8c622b;background:#faf5e9;color:#59421f;\"\u003e\n      \u003cstrong\u003eReference Note:\u003c\/strong\u003e Do not select solely by GLM 37760; verify the exhaust manifold reference and gasket shape. Sierra 18-0418 is associated with use-with manifold references 18-1957-2, 18-1982, 18-1929, 18-1933, and 18-1898—those numbers identify exhaust manifolds, not engine models or replacement numbers for this gasket.\n    \u003c\/div\u003e\n  \u003c\/section\u003e\n\n  \u003csection style=\"margin:0 0 40px;\"\u003e\n    \u003ch2 style=\"margin:0 0 18px;padding:0 0 10px;border-bottom:1px solid #bdc9c0;color:#234d40;font-family:Georgia,Times,serif;font-size:25px;font-weight:400;line-height:1.35;\"\u003eSupplied Parts\u003c\/h2\u003e\n    \u003cul style=\"margin:0;padding-left:22px;\"\u003e\n      \u003cli style=\"margin:0 0 12px;\"\u003eExhaust manifold gasket\u003c\/li\u003e\n    \u003c\/ul\u003e\n  \u003c\/section\u003e\n\n  \u003csection style=\"margin:0 0 40px;\"\u003e\n    \u003ch2 style=\"margin:0 0 18px;padding:0 0 10px;border-bottom:1px solid #bdc9c0;color:#234d40;font-family:Georgia,Times,serif;font-size:25px;font-weight:400;line-height:1.35;\"\u003eService \u0026amp; Installation Notes\u003c\/h2\u003e\n    \u003cp style=\"margin:0 0 14px;\"\u003eGeneral service guidance only. Use the service manual for your exact engine and exhaust configuration.\u003c\/p\u003e\n    \u003col style=\"margin:0;padding-left:22px;list-style-type:decimal;\"\u003e\n      \u003cli style=\"margin:0 0 12px;\"\u003eAllow the engine and exhaust system to cool completely, shut off the battery switch, and prevent accidental engine cranking before starting disassembly.\u003c\/li\u003e\n      \u003cli style=\"margin:0 0 12px;\"\u003eSupport heavy exhaust manifold components during removal and installation to avoid damaging mounting studs, bolts, or mating surfaces.\u003c\/li\u003e\n      \u003cli style=\"margin:0 0 12px;\"\u003eClean and inspect the mating faces on the exhaust manifold and cylinder head (or adapter plate). Remove old gasket material without gouging the sealing surfaces.\u003c\/li\u003e\n      \u003cli style=\"margin:0 0 12px;\"\u003eCompare the new gasket directly against the removed gasket and the sealing interface to verify port alignment and bolt hole positions. On a matching two-piece Ford 460-to-GM 454 conversion arrangement, install this gasket specifically between the adapter plate and the GM exhaust manifold.\u003c\/li\u003e\n      \u003cli style=\"margin:0 0 12px;\"\u003eTighten fasteners following the sequence and torque specifications in the engine manufacturer's service manual. After starting the engine, inspect the joint for exhaust leaks; shut down immediately and inspect if any abnormal leakage or temperature occurs.\u003c\/li\u003e\n    \u003c\/ol\u003e\n  \u003c\/section\u003e\n\n  \u003cdiv style=\"margin:0 0 40px;padding:24px;border-top:1px solid #bdc9c0;border-bottom:1px solid #bdc9c0;background:#f5f3ec;box-sizing:border-box;\"\u003e\n    \u003ch2 style=\"margin:0 0 18px;padding:0 0 10px;border-bottom:1px solid #bdc9c0;color:#234d40;font-family:Georgia,Times,serif;font-size:25px;font-weight:400;line-height:1.35;\"\u003eThe Serdamarine Approach\u003c\/h2\u003e\n    \u003cp style=\"margin:0;\"\u003eExhaust parts need a configuration match. Serdamarine focuses on marine exhaust manifolds and their related service parts. Application details, connection requirements and public reference numbers are presented together to support part selection.\u003c\/p\u003e\n  \u003c\/div\u003e\n\n  \u003csection style=\"margin:0 0 40px;\"\u003e\n    \u003ch2 style=\"margin:0 0 18px;padding:0 0 10px;border-bottom:1px solid #bdc9c0;color:#234d40;font-family:Georgia,Times,serif;font-size:25px;font-weight:400;line-height:1.35;\"\u003eQuestions Before Replacement\u003c\/h2\u003e\n    \u003cdiv style=\"margin:0;padding:18px 0;border-bottom:1px solid #dce3dc;\"\u003e\n      \u003ch3 style=\"margin:0 0 10px;color:#234d40;font-size:17px;line-height:1.5;font-weight:700;\"\u003eCan I order this gasket for any Ford 460 marine engine?\u003c\/h3\u003e\n      \u003cp style=\"margin:0;\"\u003eNo. For Ford 460 applications, this gasket is only for the adapter-plate-to-GM-exhaust-manifold joint in a specific two-piece Ford 460-to-GM 454 manifold conversion assembly. It does not fit a standard Ford 460 cylinder-head-to-manifold joint.\u003c\/p\u003e\n    \u003c\/div\u003e\n    \u003cdiv style=\"margin:0;padding:18px 0;border-bottom:1px solid #dce3dc;\"\u003e\n      \u003ch3 style=\"margin:0 0 10px;color:#234d40;font-size:17px;line-height:1.5;font-weight:700;\"\u003eIs this an exhaust elbow \/ riser gasket or a complete gasket kit?\u003c\/h3\u003e\n      \u003cp style=\"margin:0;\"\u003eNeither. Exhaust manifold gaskets and exhaust elbow\/riser gaskets are separate parts serving different joints. This listing is for the individual exhaust manifold (or adapter-plate-to-GM-manifold) gasket, not a complete manifold gasket repair kit.\u003c\/p\u003e\n    \u003c\/div\u003e\n    \u003cdiv style=\"margin:0;padding:18px 0;border-bottom:1px solid #dce3dc;\"\u003e\n      \u003ch3 style=\"margin:0 0 10px;color:#234d40;font-size:17px;line-height:1.5;font-weight:700;\"\u003eWhat are Sierra numbers 18-1957-2, 18-1982, 18-1929, 18-1933, and 18-1898?\u003c\/h3\u003e\n      \u003cp style=\"margin:0;\"\u003eThose are Sierra exhaust manifold part numbers associated as \"use-with\" assemblies for Sierra gasket 18-0418. They identify the mating exhaust manifolds rather than engine model numbers or direct gasket replacement numbers.\u003c\/p\u003e\n    \u003c\/div\u003e\n  \u003c\/section\u003e\n\n  \u003csection style=\"margin:0 0 40px;\"\u003e\n    \u003ch2 style=\"margin:0 0 18px;padding:0 0 10px;border-bottom:1px solid #bdc9c0;color:#234d40;font-family:Georgia,Times,serif;font-size:25px;font-weight:400;line-height:1.35;\"\u003eRelated Service Parts\u003c\/h2\u003e\n    \u003cp style=\"margin:0 0 14px;\"\u003eSierra reference 18-0418 lists the following associated exhaust manifold assemblies for use with this gasket style (manifolds are separate components and are not included with this gasket):\u003c\/p\u003e\n    \u003cul style=\"margin:0;padding-left:22px;\"\u003e\n      \u003cli style=\"margin:0 0 12px;\"\u003eSierra Exhaust Manifold References: 18-1957-2, 18-1982, 18-1929, 18-1933, 18-1898\u003c\/li\u003e\n    \u003c\/ul\u003e\n  \u003c\/section\u003e\n\u003c\/div\u003e","brand":"Serdamarine","offers":[{"title":"Default Title","offer_id":45172497252403,"sku":"24GK058","price":14.5,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0699\/2930\/4115\/files\/marine-exhaust-part-ac6ac11ab8c0ef7a.jpg?v=1792763653"}],"url":"https:\/\/serdamarine.com\/collections\/mercruiser-7-4l-454-cid-420hp-v-8-sterndrive-0a398941-thru-0b622418-exhaust-manifold-elbow-425-gil-system.oembed","provider":"我的商店","version":"1.0","type":"link"}