Cometic C5817-120 GM Big Block MLS Head Gasket Bore Thick - V8 4.320 120

The Cometic C5817-120 is a precision-engineered Multi-Layer Steel (MLS) cylinder head gasket designed specifically for GM Generation V and VI Big Block V8 engines. This high-performance gasket features a 4.320-inch bore diameter and .120-inch compressed thickness, making it ideal for performance builds and engine rebuilds requiring exact specifications.

Key Features:

• Multi-Layer Steel (MLS) construction for superior sealing and durability
• 4.320-inch bore diameter for precise fitment
• .120-inch (3.05mm) compressed gasket thickness
• Engineered specifically for GM Gen-V and Gen-VI Big Block V8 engines
• Provides excellent conformability to cylinder head and block surfaces
• Resists combustion gas leakage and coolant seepage
• Withstands extreme temperatures and pressures in high-performance applications

Cometic's MLS gaskets feature multiple layers of stainless steel with proprietary coatings that allow the gasket to adapt to surface imperfections while maintaining optimal sealing pressure. This design makes them particularly well-suited for forced induction, nitrous oxide, and naturally aspirated high-compression builds where reliability is critical.