SBM Head Gasket 4.140 Bore .028 thick

The SBM Head Gasket 4.140 Bore .028 thick by Mr. Gasket is a precision-engineered shim designed for Small Block Mopar engine builds and high-performance restorations. This rubber-coated steel core gasket serves a critical role in combustion chamber sealing and compression ratio tuning, making it an essential component for serious engine builders and mechanics undertaking cylinder head work. Whether you're restoring a classic Mopar muscle car or optimizing a modified small block, proper head gasket selection directly impacts engine reliability, peak horsepower delivery, and long-term durability.

Engineered with a 4.140-inch bore diameter and 0.028-inch compression thickness, this gasket shim allows fine-tuned control over combustion chamber volume—a critical variable in maximizing compression ratio without interference or detonation risk. The rubber-coated steel core construction combines structural integrity with sealing compliance, preventing combustion gas blowby while accommodating the thermal cycling and pressure cycling that naturally occurs under load. The 0.028-inch thickness places this in the mid-range shim spectrum, making it suitable for both stock-stroke and mildly stroked Mopar applications where precise compression tuning is necessary for optimal carbureted or EFI performance.

Engine builders and restoration specialists benefit most from this shim when assembling or refreshing Small Block Mopar heads—particularly 273, 318, 340, and 360 variants where compression ratio optimization can unlock significant performance gains. Installation requires careful cylinder head alignment and proper torque sequencing to ensure uniform gasket compression and seal integrity across all cylinders. This Mr. Gasket product is sold individually, allowing builders to purchase multiple units for full-block coverage or to stack shims in combination for custom compression targets. Verify bore diameter compatibility with your specific cylinder head casting before ordering.