4.500 MLS Head Gasket .075 - BBM

The 4.500 MLS Head Gasket .075 - BBM is a precision multi-layer steel cylinder head gasket engineered for Mopar B and RB-series big-block engines. This gasket is essential for anyone rebuilding or restoring a classic muscle car or performance engine, where maintaining proper compression and preventing coolant or oil leakage between the cylinder head and block is critical to reliability and longevity. Whether you're performing a top-end overhaul, addressing a blown gasket, or assembling a stroker build, this OEM-specification component ensures a factory-correct seal.

This multi-layer steel (MLS) design features a 4.500-inch bore diameter and 0.075-inch compression thickness, making it compatible with standard and mildly modified B/RB-block applications. The multi-layer construction provides superior sealing durability compared to traditional composite gaskets, resisting blow-by, thermal cycling, and the mechanical stress of high-rpm operation. The 0.075-inch thickness is calibrated to maintain correct piston-to-head clearance and combustion chamber volume, which directly affects compression ratio and detonation resistance—critical variables in tuning and engine performance. MLS gaskets demand proper deck surface preparation and torque sequencing for optimal sealing integrity.

This gasket is ideal for mechanics and enthusiasts rebuilding 318, 340, 360, 383, 400, 413, 426, and 440 Mopar engines, or any B/RB-series block with a 4.500-inch bore. Proper installation requires cleaning both the block and head to bare metal, using a torque wrench with a documented sequence, and adhering to manufacturer specifications for fastener tightness. Keep this gasket on hand as a critical wear item during any significant engine work, coolant system repair, or performance build where factory-spec sealing performance is non-negotiable.