Shim Kit - 1.500 Dia. .645 ID (64pcs)

The Shim Kit - 1.500 Dia. .645 ID (64pcs) by PAC Racing Springs is an essential valve spring tuning component for serious engine builders and performance mechanics. These precision shims are designed to fine-tune valve spring installed height and preload tension, critical factors that directly affect valvetrain stability, cam lobe contact pressure, and overall engine reliability at high RPM. Whether you're building a naturally aspirated street engine, preparing a race motor, or dialing in a rebuild, this 64-piece assortment gives you the flexibility to achieve exact specifications without compromising performance or durability.

Manufactured from hardened steel, the Shim Kit features a 1.500-inch outer diameter and 0.645-inch inner diameter, engineered to stack securely around the valve spring seat without slippage or misalignment. The kit includes multiple thickness options—0.015, 0.020, 0.030, and 0.050 inches—allowing precision adjustment in controlled increments. This modular approach eliminates guesswork during setup; you can combine shims to reach exact installed height targets and achieve the correct spring pressure curve for your camshaft duration and lift specifications. Steel construction ensures these shims withstand repeated valve cycling, maintain dimensional stability under heat and load, and resist deformation from aggressive valve events.

Professional engine builders, performance shops, and dedicated enthusiasts rely on PAC Racing Springs shim kits during cylinder head assembly and top-end rebuilds. The 64-piece quantity provides enough variety to service multiple cylinder heads or stock a shop inventory for recurring jobs. Installation involves stacking shims between the valve spring retainer and the spring seat to adjust preload and height; precise selection ensures consistent rocker arm geometry, prevents coil bind, and maintains proper pushrods or rocker arm angles. Compatible with most domestic and import small-block and big-block engines using standard spring seats, this kit is indispensable for any builder committed to durability and peak performance.