I have an early set of Offenhauser heads with vertical water outlets. I'd really like to use, but my machinist had to take .010 (ten thousands) off to clean up the worst pitting. this is more than I suspected, is this too much to work with? I don't really want compression higher that 9 or 9.5 to 1. can I make this up with a gasket/spacer? different pistons etc.... sorry I'm a newbie to flatheads, fyi I have 4" mercury crank I'm considering using also. I'm either going to get 2nd head done the same, or turn into wall art... thanks for an input..
Mill the other one the same, and use the thickest head gaskets you can find. .010 isn't very much. As long as the pistons and valves don't hit the heads, you're OK. Check the clearances with modelling clay if you are really worried.
I suggest that you clay the heads to be sure you have enough clearance between the heads and pistons/ valves. You want .040 -.050 clearance. Those long skinny flathead connecting rod stretch a good bit at 4000 RPM.
also, how does one know that the .010 removed isnt additional to an unknown number possibly removed sometime in the 50+ year history of the heads?
thanks for the quick reply's, I called and am getting the other head done. who knows the history of these heads, I will verify clearances.
Ten thousandths is very little. Install just the heads with no gaskets. Turn the engine slowly by hand. If nothing hits, just installing the gaskets should give you sufficient clearance to run. I'm no expert on early Offy heads, but I don't think 9-9.5:1 compression is even possible without some serious machine work on a modified engine.
You do not know what your clearance is without putting the heads on with gaskets and using clay or the other technique that I learned about on Fordbarn is a ball of tin foil. Pistons make a lot of difference, too. I think that there have been many clearance problems discussed involving Egge pistons.
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