4.125 MLS Head Gasket .040 - GM LS1

The Cometic Gaskets 4.125 MLS Head Gasket .040 for GM LS1 engines is a high-performance sealing solution designed for serious LS builders and performance shops. This gasket is essential for applications where maximum cylinder pressure integrity is critical, whether for stock replacements, high-RPM race engines, or street/strip hybrids.

Constructed from Multi-Layer Steel (MLS), this gasket features a .040-inch thickness that helps maintain controlled compression ratios while ensuring a reliable seal against the cylinder head and block. The elastomer-coated facings resist blow-by and maintain gasket crush even under extreme thermal cycling and combustion events, making it suitable for turbocharged, supercharged, or nitrous-assisted applications.

Ideal for any LS1 rebuild, this gasket supports stock restorations, mild street builds, and serious competition engines, preserving OEM or modified compression ratios without the need for extensive block or head decking adjustments. Its design is optimized for the LS platform, ensuring that builders can achieve repeatable performance in their builds.