4.380 MLS Head Gasket .040 - Pontiac 400/455

The Cometic Gaskets 4.380 MLS Head Gasket .040 is a multi-layer steel cylinder head gasket engineered for Pontiac 400 and 455 V8 engines. MLS (Multi-Layer Steel) head gaskets represent the modern standard for high-performance and high-mileage engine sealing, combining the reliability of proven steel construction with superior conformability to warped or aged cylinder heads.

With a 4.380-inch bore diameter and 0.040-inch compression thickness, this gasket is specifically sized to match the displacement and combustion chamber geometry of Pontiac's legendary big-block platform. The multi-layer steel construction distributes clamping load more evenly across the gasket face than traditional composition gaskets, reducing the likelihood of localized hot spots and combustion gas leakage—a critical advantage for engines subjected to sustained high cylinder pressures or thermal cycling. The 0.040-inch thickness provides the precise compression ratio spec for stock or mildly modified Pontiac 400/455 applications.

This gasket is the correct choice for rebuilding or resealing Pontiac 400 and 455 engines in muscle cars, vintage trucks, and hot rod builds. Engine builders and restoration specialists rely on Cometic MLS gaskets for their predictable sealing performance and compatibility with both stock and ported cylinder head surfaces. Whether performing a complete head gasket replacement on an original muscle car or freshening a high-mileage stroker, this gasket delivers the engineering precision demanded by serious Pontiac V8 work.

Pontiac big-block engines remain popular in restoration and performance applications because of their robust casting and strong torque characteristics. Cometic's MLS head gasket technology ensures that sealing integrity matches the durability expectations of these classic powerplants, whether the engine is stock original or upgraded with modern ignition and fuel management systems.