4.380 MLS Head Gasket .051 - BBM

The Cometic Gaskets 4.380 MLS Head Gasket .051 – BBM (part number C5461-051) is a precision multi-layer steel cylinder head gasket engineered for Mopar B and RB-series engines. This gasket combines a 4.380-inch bore diameter with a 0.051-inch compression thickness, delivering the sealing performance and dimensional consistency demanded by high-compression and modified engine builds. MLS (multi-layer steel) construction provides superior durability and reusability compared to traditional single-layer designs, making it the preferred choice for street performance and racing applications where engine reliability is non-negotiable.

The 0.051-inch thickness spec is critical for maintaining proper compression height and piston-to-valve clearance in Mopar B and RB blocks. MLS gasket technology uses spring-steel layers and elastomer coating to handle thermal cycling and combustion pressures without creep or blow-by, even in aggressive tune scenarios. The 4.380-inch bore sizing is OEM-correct for many big-block Mopar applications, ensuring dead-accurate fit with zero guesswork. Each gasket ships individually, allowing builders to purchase exactly what their project requires without excess inventory.

This gasket addresses the needs of classic car restorers, hot rod builders, and engine rebuilders working with Mopar B-block (383, 400) and RB-block (440, 413, 426) powerplants. Whether you're doing a stock rebuild, a street performance refresh, or a competition engine, correct gasket selection prevents coolant and oil leaks that compromise reliability. Cometic's reputation in precision gasket manufacturing means this part meets tight tolerances that ensure consistent clamp load distribution and long-term sealing integrity.