Sierra 18-3887 Head Gasket - Replaces 27-75611 for GM 305 (5.0L)/350 (5.7L) CID Engines

The Sierra 18-3887 Head Gasket is a direct-fit replacement head gasket engineered for GM 305 (5.0L)/350 (5.7L) CID marine engines. It seals the joint between the cylinder head and engine block, maintaining compression and preventing coolant or combustion gas leaks that can lead to overheating, loss of power, or engine damage. Installing a correctly specified head gasket is critical on marine engines, where consistent sealing under heat cycling and vibration keeps the powerhead running reliably.

This gasket is sold as a direct cross-reference replacement for several OEM and aftermarket part numbers, making it easy to source the correct gasket even if your old part was originally sold under a different number. It ships as a single gasket, ready to install as part of a head gasket or top-end rebuild job on a compatible GM 305/350 CID marine engine.

Specifications

• Brand: Sierra
• Manufacturer Part Number: 18-3887
• Product Type: Head Gasket
• Fitment: GM 305 (5.0L)/350 (5.7L) CID engines
• Replaces (OEM): 27-75611, 27-75611001, 27-48330, 27-34278
• Weight: 0.48 pounds
• Shape: Round
• Color: White
• UPC: 808282258955

Fitment

• GM 305 (5.0L)/350 (5.7L) CID engines

Replaces (OEM)

• 27-75611
• 27-75611001
• 27-48330
• 27-34278

Frequently Asked Questions

What engines does the Sierra 18-3887 head gasket fit? The Sierra 18-3887 head gasket is designed for GM 305 (5.0L)/350 (5.7L) CID marine engines.

What OEM part numbers does 18-3887 replace? 18-3887 is a direct replacement for OEM numbers 27-75611, 27-75611001, 27-48330, and 27-34278.

Is the 18-3887 gasket sold as a single unit? Yes, the 18-3887 ships as one head gasket, not a full engine gasket set.

How much does the 18-3887 head gasket weigh? This head gasket weighs 0.48 pounds.

What shape is the Sierra 18-3887 head gasket? The 18-3887 is a round head gasket.

What color is the 18-3887 head gasket? The gasket is white in color.

Can I use 18-3887 if my old gasket has a different part number stamped on it? Yes, as long as your old gasket's number is one of 27-75611, 27-75611001, 27-48330, or 27-34278, the Sierra 18-3887 is the correct cross-reference replacement.

Is Sierra 18-3887 a genuine or aftermarket part? Sierra 18-3887 is an aftermarket head gasket manufactured to match the fit and sealing performance of the OEM numbers it replaces.

Will 18-3887 fit a 454 CID engine? No, 18-3887 is specified for GM 305 (5.0L)/350 (5.7L) CID engines, not 454 CID engines.

What is the UPC for the Sierra 18-3887 head gasket? The UPC for the Sierra 18-3887 head gasket is 808282258955.