I have had my Cylinder Head milled two times since I've had it due to excessive heat/warpage over the last year. The first time when my motor had 118K miles and the second time when my new shortblock recently let loose. My question is what is the minimum thickness for safety in terms of the Cylinder Head measurement? Ryan Woon has my shortblock and told me that he had to mill .006 off of it to get it true again and my machine shop just milled .004 off the Cylinder Head. How much was milled off the Cylinder Head the first time I don't know. The Cylinder Head now measures 4.748" from Valve Cover surface to head, then one must calculate that .006 was taken off the Block. Am I in unsafe waters with this? Is there a thicker head gasket that could be used? I'm probably going to just have my installer test the clearances either with clay or by installing weaker springs which would enable him to pust the valve down by hand to test. Here's the real kicker: According to the spreadsheet provided by the Engine Builders Association for the 2JZ-GTE, the stock Cylinder Head Thickness is 4.570. How in the hell can that be when mine has been milled twice and is still thicker? If the new thickness according to spec is 4.570' (116.078mm) and the minimum thickness is 4.560 (115.824mm) then that leaves me with about .010 safety barrier? Oh shit!