4.125 MLS Head Gasket .040 - SBC

The Cometic Gaskets 4.125 MLS Head Gasket .040 is a multi-layer steel cylinder head gasket engineered for small block Chevy engines. This precision-manufactured gasket maintains a critical 0.040-inch compression thickness designed to deliver proper clamping load and combustion sealing across the entire bore diameter. MLS head gaskets represent the modern standard for high-performance and rebuilt engines, offering superior durability and sealing consistency compared to traditional composite gaskets.

The 4.125-inch bore specification makes this gasket suitable for standard small block Chevy applications where bore diameter tolerance is critical. The multi-layer steel construction resists thermal cycling, preventing gasket creep and combustion gas blowby—common failure modes in older single-layer designs. The 0.040-inch thickness is precisely calibrated; thicker gaskets lower compression ratio and alter ignition timing requirements, while thinner gaskets increase compression but demand exact machining surface flatness. This specification requires that cylinder heads and blocks meet Cometic's published flatness and finish standards for reliable sealing.

This gasket is intended for engine builders, machine shops, and enthusiasts performing small block Chevy rebuilds or upgrades. Whether assembling a stock restoration, mild performance build, or street engine, proper head gasket selection prevents leaks and protects your investment in machine work. Cometic gaskets are sold individually, so confirm your engine configuration and ordering requirements before purchase.

Small block Chevy engines span decades of production with multiple bore sizes and deck heights. Verify your exact bore diameter and compression thickness requirement against your cylinder head machining specifications or engine builder's recommendation. Incorrect gasket thickness or bore diameter can compromise sealing and engine performance.