Cam Tower Spacers .060″ - .080" (1.5mm - 2.0mm)
When you mill the head to raise compression (or simply to clean it up), you should want to shim the cam towers, so as to keep the chain geometry the same as stock height. Also, when you put thick cam tower spacers, you should be using longer bolts. These bolts are not only longer, but also higher torque spec—ideal for performance use.
Shims: .060″ (1.5mm).