Re: Straight 8 Head Modifications
Posted by Eric Boyle on 2009/4/11 2:15:17
There are plenty of folks out there who have milled a Packard head 0.030" and bent the valves as they hit the head because they failed to consider if the head had been previously milled. And then you can be in a real pickle, new heads are rare, and double-gasketing or useing extra thick custom head gaskets doesn't usually work for long.
What's wrong with leaving it stock?
Pull the head, get some clay and put it on top of the valves. Turn the engine over several times, then pull the head. Measure the thickness of the clay to find out the clearance between the head and the valve. Simple as that.
Another solution, and one I approve, but if you go too far it will lower the c/r, and that is to polish the combustion chamber in the head. I plan on doing this on the head on the Speedster, as it will get rid of possible hot spots caused by casting flash. I'm not too worried about compression, as I plan on forced induction. (along with larger valves that will probably require clearance grinding anyway)
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