Cometic C5638-040 MLS Cylinder Head Gasket 4.500" Bore GM Mercury Marine Gen-IV Big Block V8

The Cometic C5638-040 is a premium multi-layer steel (MLS) cylinder head gasket engineered specifically for GM/Mercury Marine 1050 Gen-IV big block V8 applications. This high-performance gasket features a 4.500-inch bore diameter and .040-inch compressed thickness, making it ideal for both marine and high-output automotive applications.

Advanced MLS Construction:

• 3-layer stainless steel design provides superior strength and durability
• Viton-coated outer layers deliver exceptional sealing in harsh marine environments
• Heat resistant to 482°F (250°C) for extreme performance applications
• Excellent rebound characteristics and corrosion resistance
• Valve pocketed bore shape for precise combustion chamber sealing

Key Specifications:

• Bore size: 4.500 inches
• Compressed thickness: .040 inches (1.0mm)
• Material: Multi-layer stainless steel with Viton coating
• Features 2 slotted lifter valley bolt holes
• Sold individually

Cometic MLS gaskets are designed to withstand extreme cylinder pressures and provide superior sealing performance without the need for additional sealants. The multi-layer construction allows the gasket to handle the thermal expansion differences between aluminum heads and cast iron blocks, making it ideal for marine applications where reliability is critical. This gasket installs dry and requires no retorquing after initial installation.