4.540 MLS Head Gasket .040 - BBC

The Cometic Gaskets 4.540 MLS Head Gasket .040 for Big Block Chevy is a multi-layer steel cylinder head gasket engineered for high-performance and racing applications. This .040-inch compression thickness gasket delivers the sealing integrity required in demanding engine builds, whether for street performance, competition, or restoration of classic Big Block Chevy platforms.

The 4.540-inch bore specification matches common BBC cylinder head configurations and accommodates larger displacement combinations. Multi-layer steel (MLS) construction provides superior conformability to both head and block surfaces, reducing the risk of combustion gas leakage and coolant bypass—critical concerns in high-boost or high-nitrous applications. The .040-inch thickness is a popular choice for engines running modest to moderate compression ratios and is compatible with standard BBC deck heights. Cometic's manufacturing tolerances ensure consistent performance across multiple gasket replacements, a key consideration for builders who plan future rebuilds or cylinder head work.

This gasket is suited for Big Block Chevy engine builders, restoration shops, and performance enthusiasts tackling mid-level displacement builds or refreshes. It fits BBC heads across generations and is commonly used in street performance engines, vintage race cars, and marine applications. A fresh gasket eliminates variables when diagnosing existing leaks or ensuring reliability after head work, making it an essential component for any serious BBC rebuild or refresh.

BBC head gasket selection depends on bore size, compression height, and intended application. Cometic's MLS design and proven track record in both street and racing environments make this gasket a recognized choice among BBC builders seeking dependable sealing without compromises to performance or durability.