{"product_id":"head-gasket-for-gm-454-7-4l-marine-engines-replaces-oem-30266-sierra-18-3874","title":"Sierra Head Gasket 18-3874, Replaces 30266, for GM 454 (7.4L) CID Engines","description":"\u003cp\u003eThe Sierra Head Gasket 18-3874 is a marine engine head gasket engineered to seal the joint between the cylinder head and engine block on GM 454 (7.4L) CID marine engines. Proper sealing at this joint is critical for maintaining compression, preventing coolant and oil intermixing, and protecting against combustion gas leakage that can lead to overheating or engine damage. This head gasket is manufactured to OEM specifications, allowing it to serve as a direct replacement in the position originally filled by the engine's factory gasket.\u003c\/p\u003e\u003cp\u003eThis part is sold priced per package and is designed as a direct cross-reference replacement for OEM part number 30266, making it straightforward to identify and order the correct gasket for a GM 454 (7.4L) CID engine rebuild or head gasket replacement job. Sierra is a long-established supplier of marine engine parts, and this gasket is intended for marine inboard applications using the GM 454 (7.4L) CID engine block.\u003c\/p\u003e\u003ch3\u003eSpecifications\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eBrand:\u003c\/strong\u003e Sierra\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eManufacturer Part Number:\u003c\/strong\u003e 18-3874\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eItem Type:\u003c\/strong\u003e Head Gasket\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eCategory:\u003c\/strong\u003e Mercruiser Head Gaskets\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eWeight:\u003c\/strong\u003e 0.47 pounds\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eUPC:\u003c\/strong\u003e 808282241667\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eEngine Fitment:\u003c\/strong\u003e GM 454 (7.4L) CID Eng.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003ePackaging:\u003c\/strong\u003e Priced per Package\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eReplaces (OEM):\u003c\/strong\u003e 30266\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eFitment\u003c\/h3\u003e\u003cul\u003e\u003cli\u003eGM 454 (7.4L) CID Eng.\u003c\/li\u003e\u003c\/ul\u003e\u003ch3\u003eReplaces (OEM)\u003c\/h3\u003e\u003cul\u003e\u003cli\u003e30266\u003c\/li\u003e\u003c\/ul\u003e\u003ch3\u003eFrequently Asked Questions\u003c\/h3\u003e\u003cp\u003e\u003cstrong\u003eWhat engine does the Sierra 18-3874 head gasket fit?\u003c\/strong\u003e The Sierra 18-3874 head gasket is designed for GM 454 (7.4L) CID marine engines.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eDoes 18-3874 replace OEM part number 30266?\u003c\/strong\u003e Yes, Sierra 18-3874 is a direct replacement for OEM number 30266.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eHow much does the 18-3874 head gasket weigh?\u003c\/strong\u003e It weighs 0.47 pounds.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eIs this head gasket sold individually or in a package?\u003c\/strong\u003e The Sierra 18-3874 head gasket is priced per package.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat is the UPC for the Sierra 18-3874 head gasket?\u003c\/strong\u003e The UPC for this head gasket is 808282241667.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eIs the Sierra 18-3874 an OEM-spec gasket?\u003c\/strong\u003e Yes, this head gasket is manufactured to OEM specifications for GM 454 (7.4L) CID engines.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eCan I use 18-3874 on a smaller GM engine like the 305 or 350?\u003c\/strong\u003e No, the 18-3874 head gasket is specified for GM 454 (7.4L) CID engines, not the 305 or 350 CID engines, which use different Sierra part numbers.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat category does the 18-3874 head gasket fall under?\u003c\/strong\u003e This part is listed under Mercruiser Head Gaskets.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWill the 18-3874 head gasket seal correctly against oil and coolant leaks?\u003c\/strong\u003e The Sierra 18-3874 is designed to seal the cylinder head to block joint on a GM 454 (7.4L) CID engine, preventing coolant and combustion gas leakage when properly installed.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat brand makes part number 18-3874?\u003c\/strong\u003e Sierra manufactures the 18-3874 head gasket.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eIs 18-3874 the only cross-reference number for this gasket?\u003c\/strong\u003e The listed OEM cross-reference for Sierra 18-3874 is 30266.\u003c\/p\u003e","brand":"Sierra","offers":[{"title":"Default Title","offer_id":48988168650971,"sku":"SIE-18-3874","price":83.71,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0839\/7586\/4539\/files\/SIE-18-3874_lg__39454.1692043921.500.750.jpg?v=1785188254","url":"https:\/\/www.goodvibesmarina.com\/products\/head-gasket-for-gm-454-7-4l-marine-engines-replaces-oem-30266-sierra-18-3874","provider":"Good Vibes Marina","version":"1.0","type":"link"}