How much material can be removed when skimming a cylinder head?

When skimming a cylinder head, typically, a maximum of 0.020 to 0.030 inches (0.5 to 0.76 mm) can be removed without compromising the structural integrity or affecting the engine's performance. However, the specific amount depends on the manufacturer's specifications and the condition of the head. It's crucial to check for warping and to ensure that the head remains within acceptable tolerances to maintain proper sealing and compression. Always consult the service manual for the specific engine to determine the maximum allowable skimming.