Sierra Head Gasket 18-3874, Replaces 30266, for GM 454 (7.4L) CID Engines

The 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.

This 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.

Specifications

• Brand: Sierra
• Manufacturer Part Number: 18-3874
• Item Type: Head Gasket
• Category: Mercruiser Head Gaskets
• Weight: 0.47 pounds
• UPC: 808282241667
• Engine Fitment: GM 454 (7.4L) CID Eng.
• Packaging: Priced per Package
• Replaces (OEM): 30266

Fitment

• GM 454 (7.4L) CID Eng.

Replaces (OEM)

• 30266

Frequently Asked Questions

What engine does the Sierra 18-3874 head gasket fit? The Sierra 18-3874 head gasket is designed for GM 454 (7.4L) CID marine engines.

Does 18-3874 replace OEM part number 30266? Yes, Sierra 18-3874 is a direct replacement for OEM number 30266.

How much does the 18-3874 head gasket weigh? It weighs 0.47 pounds.

Is this head gasket sold individually or in a package? The Sierra 18-3874 head gasket is priced per package.

What is the UPC for the Sierra 18-3874 head gasket? The UPC for this head gasket is 808282241667.

Is the Sierra 18-3874 an OEM-spec gasket? Yes, this head gasket is manufactured to OEM specifications for GM 454 (7.4L) CID engines.

Can I use 18-3874 on a smaller GM engine like the 305 or 350? 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.

What category does the 18-3874 head gasket fall under? This part is listed under Mercruiser Head Gaskets.

Will the 18-3874 head gasket seal correctly against oil and coolant leaks? 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.

What brand makes part number 18-3874? Sierra manufactures the 18-3874 head gasket.

Is 18-3874 the only cross-reference number for this gasket? The listed OEM cross-reference for Sierra 18-3874 is 30266.