BBM Head Gasket - 4.365 .021

The BBM Head Gasket - 4.365 .021 is a precision-engineered gasket shim built to meet the demanding specifications of high-performance Mopar 426 Hemi engines. Designed for serious mechanics and engine builders who understand that head gasket selection directly impacts combustion chamber sealing, bore alignment, and overall engine longevity, this FEL-PRO component delivers OEM-quality performance. Whether you're performing a complete engine rebuild, diagnosing a compression loss issue, or fine-tuning compression ratio for forced induction applications, the correct gasket thickness is non-negotiable.

This head gasket shim features a 4.365-inch bore diameter with a 0.021-inch compression thickness—a specification that ensures proper clamping load distribution and maintains critical combustion sealing across all eight cylinders. The rubber-coated steel core construction provides the durability and thermal resistance required in extreme-duty applications, preventing blow-by and coolant leakage even under high boost pressures or sustained high-RPM operation. FEL-PRO's manufacturing precision guarantees consistent thickness tolerance, which is essential when stacking multiple gaskets or using shims to achieve target compression ratios in modified 426 Hemi platforms.

Engine builders and restoration specialists working on vintage Mopar muscle cars and modern Hemi swaps rely on this gasket for its compatibility with both original equipment and aftermarket cylinder head packages. The 0.021-inch thickness makes it ideal for compression adjustments, head resurfacing corrections, or as a replacement component in full gasket sets. Proper installation requires accurate deck surface preparation, correct bolt torque sequences, and verification of bore concentricity—standard procedures that separate successful builds from field failures. Stock this FEL-PRO component for any serious Hemi work.