Spacer Package

The Mopar Performance Spacer Package is a precision rocker arm shim set engineered for Mopar 426 Hemi engine builds and high-performance restorations. This spacer package consists of 12 individual round shims, each 0.878 inches in inner diameter and 0.015 inches thick, designed to fine-tune valve train geometry and maintain critical clearances between rocker arms and cylinder heads. Serious engine builders and restoration shops rely on these shims to achieve proper pushrod geometry, reduce unwanted contact points, and ensure consistent valve actuation across all eight cylinders.

Manufactured from hardened steel, each shim in this Spacer Package delivers the durability and dimensional stability required in high-RPM and high-boost engine environments. The 0.015-inch thickness is purposefully engineered to address common rocker arm geometry issues without requiring complete valve train redesign. When installed between the rocker arm and mounting surface, these shims compensate for manufacturing tolerances, aftermarket head modifications, and custom pushrod lengths—all critical factors in maximizing valve lift accuracy and preventing rocker arm bind. The round profile and precision bore ensure concentric seating and repeatable performance across multiple installations.

Professional engine builders, Mopar enthusiasts, and restoration specialists depend on the Spacer Package when assembling 426 Hemi mills for both street and competition duty. Installation is straightforward—position shims under rocker arm pedestals before final torqueing—making them ideal for mid-build adjustments when initial test fits reveal geometry inconsistencies. The set of 12 shims provides sufficient quantity for a complete eight-cylinder engine plus spares for future builds. Correct rocker arm spacing is non-negotiable in high-performance applications; these shims ensure your valve train operates within engineered specifications and delivers the reliability expected from a legendary Mopar platform.