Valve Spring Shims, Spacers & Seats

If the distance from the base of the valve spring to the bottom of the valve spring retainer is too long, the spring will be too loose and if the distance is too short, coil bind will result. Valve spring shimming with spacers and seats is needed to properly set up the correct spring height and optimize engine performance, ensuring longer valve train life.

Valve spring cups (with an inside or outside shoulder type) and locators help support and hold the valve spring diameter in place throughout the engine rpm range to ensure proper valvetrain operation. Without these components, the springs can "walk", which will lead to damage or erratic engine performance.

The cylinder head valve seat is the surface that the intake and exhaust valve rests and seats against when it is closed. When the valve is closed, the valve seat forms a seal around it, which allows combustion pressure to build, resulting in engine power.

There are several different visual checks on valve seats that can be performed to confirm their condition. When the valve is closed it should contact the seat all the way around. With the valve springs removed, a good valve can be put into the guide and with a good push, the valve should bounce off of the seat to indicate a good setup. If the valve sticks in the seat or doesn't contact completely around the valve seat, the valve and seat needs attention.

Valve spring shims are flat circular discs that are installed under the valve spring to raise its height to the proper level. Valve spring shim kits include shims of varying heights to cover any combination that would be needed to reach the correct valve spring installed height.

Valve spring shim thickness can be determined with a digital dial caliper or other precision measurement instrument. These tools work by sliding the "fingers" around the thickness of the shim and provide a readout in millimeters or in a decimal format of the height.