4.125 MLS Head Gasket .040 - GM LS1

The Cometic Gaskets 4.125 MLS Head Gasket .040 for GM LS1 engines is a precision-engineered cylinder head gasket designed for high-performance and stock LS-series applications. MLS (Multi-Layer Steel) construction delivers superior sealing reliability across extended temperature and pressure cycles, making it the preferred choice for both street and competition builds where gasket durability under sustained load is critical.

The 0.040-inch compression thickness is engineered to maintain proper combustion chamber volume and preserve OEM-specification compression ratios on LS1 platforms, a key consideration when replacing head gaskets on stock or lightly modified engines. The 4.125-inch bore diameter matches LS1 cylinder head specifications precisely. MLS gasket design prevents combustion gas blowby and coolant seepage through multiple elastomer-coated steel layers that work together under clamping load—a proven technology that outperforms conventional single-layer designs in high-heat environments. The gasket is supplied individually, allowing builders to purchase exactly the quantity needed for their project.

This gasket is intended for LS1 engine rebuilds, head replacement, or gasket refresh on street cars, race vehicles, and engine shops where OEM-equivalent sealing performance is required. LS1 owners performing top-end work, upgrading to aftermarket cylinder heads, or addressing coolant leaks will find this Cometic gasket meets the technical requirements for reliable, leak-free operation. Proper head bolt torque sequence and specification are essential for optimal gasket performance and should be verified against your engine manual before installation.