{"product_id":"sierra-18-1986-1-exhaust-manifold-replaces-oem-3857723-fits-gm-small-block-v8-305-350-cu-in","title":"Sierra Exhaust Manifold 18-1986-2, Replaces OE 3857723, Fits GM Small Block V8 305-350 cid","description":"\u003cp\u003eThe Sierra Exhaust Manifold 18-1986-2 is a cast iron marine exhaust manifold engineered for GM Small Block V8 engines in the 305 to 350 cubic inch range, a common power plant configuration in stern-drive and inboard boat applications. Exhaust manifolds route hot exhaust gases away from the engine block while providing the water-jacketed cooling passages marine engines require to keep exhaust components safe to operate near fuel, bilge, and crew areas. This manifold is built to meet or exceed the performance of the original equipment part it replaces, using cast iron construction for the strength and heat tolerance the marine exhaust environment demands.\u003c\/p\u003e\u003cp\u003eThis manifold pairs with the corresponding manifold gasket and mounting kit for a complete installation, so buyers replacing an aging or cracked manifold can source the matching hardware at the same time. It is designed as a direct fit for GM Small Block V8 305-350 cid engines, making it a straightforward swap for boat owners maintaining stern-drive and inboard exhaust systems.\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 18-1986-2\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eProduct Type:\u003c\/strong\u003e Exhaust Manifold\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eMaterial:\u003c\/strong\u003e Cast Iron\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eEngine Application:\u003c\/strong\u003e GM Small Block V8 305-350 cu in\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eOEM Cross Reference:\u003c\/strong\u003e 3857723\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eCompatible Manifold Gasket:\u003c\/strong\u003e 18-2949\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eCompatible Mounting Kit:\u003c\/strong\u003e 18-8502\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eWeight:\u003c\/strong\u003e 40.1 pounds\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eUPC:\u003c\/strong\u003e 808282391232\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eFitment\u003c\/h3\u003e\u003cul\u003e\u003cli\u003eGM Small Block V8, 305-350 cubic inch engines\u003c\/li\u003e\u003c\/ul\u003e\u003ch3\u003eReplaces (OEM)\u003c\/h3\u003e\u003cul\u003e\u003cli\u003e3857723\u003c\/li\u003e\u003c\/ul\u003e\u003ch3\u003eFrequently Asked Questions\u003c\/h3\u003e\u003cp\u003e\u003cstrong\u003eWhat engines does the Sierra 18-1986-2 exhaust manifold fit?\u003c\/strong\u003e The 18-1986-2 manifold is built for GM Small Block V8 engines in the 305 to 350 cubic inch range, a common configuration in stern-drive and inboard marine engines.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat OEM part number does this manifold cross-reference?\u003c\/strong\u003e It cross-references OEM number 3857723, so if your original manifold carries that number, the 18-1986-2 is a direct equivalent.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eHow much does the 18-1986-2 manifold weigh?\u003c\/strong\u003e This exhaust manifold weighs 40.1 pounds.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat is the manifold made of?\u003c\/strong\u003e The 18-1986-2 is made of cast iron, chosen for its strength and heat resistance in the marine exhaust environment.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eDo I need a separate gasket to install this manifold?\u003c\/strong\u003e Yes, the 18-1986-2 manifold is installed with manifold gasket 18-2949, which is sold separately.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eIs a mounting kit required for installation?\u003c\/strong\u003e Installation uses mounting kit 18-8502 alongside the 18-1986-2 manifold and its gasket.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eIs this a genuine Sierra part or an aftermarket copy?\u003c\/strong\u003e The 18-1986-2 is a genuine Sierra manifold engineered to meet or exceed the original equipment part it replaces.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat comes in the box with this manifold?\u003c\/strong\u003e The package includes the 18-1986-2 cast iron exhaust manifold; the manifold gasket (18-2949) and mounting kit (18-8502) are separate items.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWill this manifold work with other engine sizes besides 305-350 cid?\u003c\/strong\u003e The 18-1986-2 is specified for GM Small Block V8 engines in the 305 to 350 cubic inch range; it is not listed for other displacements.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhy would I need to replace my exhaust manifold?\u003c\/strong\u003e Marine exhaust manifolds like the 18-1986-2 are commonly replaced when the original develops cracks, corrosion, or coolant leaks from age and constant heat cycling.\u003c\/p\u003e","brand":"Sierra","offers":[{"title":"Default Title","offer_id":48988089614555,"sku":"SIE-18-1986-2","price":399.24,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0839\/7586\/4539\/files\/SIE-18-1986_lg__16636.1733495359.500.750.jpg?v=1785188062","url":"https:\/\/www.goodvibesmarina.com\/products\/sierra-18-1986-1-exhaust-manifold-replaces-oem-3857723-fits-gm-small-block-v8-305-350-cu-in","provider":"Good Vibes Marina","version":"1.0","type":"link"}