Valve Shim Selection

WARNING: This page is about a different variant/trim than selected.

IMPORTANT: In order to maintain the specified valve clearance the proper shim must be selected. Perform the following procedure in order to select the proper shim:

Determine the valve(s) clearances that were out of specifications.
Remove the shim(s) from the out of specification valves.

Fig 1: Measuring Thickness Of Removed Shim Using J 26900-13 & J 8001

Courtesy of GENERAL MOTORS CORP.

Use a J 26900-13 and J 8001 to measure the thickness of the removed shim. See Special Tools .
After measuring the shim, determine the size of the replaced shim according to the formula as follows:
- A = Thickness of used shim
- B = Measured valve clearance
- C = Thickness of new shim
  Intake Valve: C= A + (B - 0.13 mm (0.0051 in)) x 1.5
  
  Exhaust Valve: C = A + (B - 0.27 mm (0.0106 in)) x 1.5
  
  Shims are available in 41 size increments of 0.020 mm (0.0008 in), from 2.000 mm (0.0787 in) to 2.800 mm (0.1102 in).
After selecting the proper shim, re-measure the valve clearance.
Install the cylinder head cover. Refer to the installation instructions in Cylinder Head Cover Replacement .