Shave the heads

We used to do 60thou back in the old days. You have to be careful, too much can restrict the flow too much from the valves to piston.
 
You need to measure the clearance before you do anything. This has been covered many times. Your looking for around .050 over the pistons and a little more over the valves.
 
I shaved 50 thousands off my 8BA heads and using an Isky Max 1 it gets a little close in there. As the guys said be sure to check the clearances.
 
am i correct in saying the only way to check the amount a material removed from a head is do a CC check?
 
The reason for milling the heads is to improve turbulence in the combustion chamber. The increase in CR is negligible. However this improved throttle response an economy.
 
If I understand your question, the answer is NO. Checking the volume of the combustion chamber - in cubic centimeters (or CC's) will not tell you how much you can safely remove from the gasket surface of the cylinder head. You need to determine the distance between the cylinder head and the piston at TDC and between the cylinder head and the valves when they are at their maximum opening. You should have .050" clearance between the head and these points. The amount you have in excess of .050" is the amount you can remove. I just did this job and was surprised at the amount of variation between cylinders.
 
RJD,
It's especially important to check the clearance on the outside edge of the combustion chamber when you bore a lot. The cylinder can be bigger than than the chamber in the head. Check this with a big bore gasket. Also when you mill the head, the fly cut area over the piston will get smaller in dia., causing the same problem, good luck Chuck.
 
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