forget the av gas...does NOT work well the specific gravity is way wrong for automotive/marine engines...will help some but not as much as expected...at this point would make no sense to me to try to run this compression ratio...short of changing the pistons the only head you can get away with would be the extra large chamber 71-72 454 365oval port or 425 rect port..if you can find them...and they are not a very good head either..but would get the compression down to a managable amount...

Man it looks like those cylinders were running lean and hot, there is a whole lot of clean area on those pistons.

what should be the fuel preassure? the pistons are brand new, have only a few hours on the, break in basically. Im seriously considering changing the pistons. Im still waiting for the machine shop to get back to me, talked to them todday and they said the valves were perffect.
bore is 4.530 stroke 4.00

MILL the piston tops.

I thought you said the valve seats where gone. That is why I am interested in what happened.

Fuel pressure should be at 6 or 7 psi . I am curious as to what heads you are running . Only because they sure look like closed chamber piston's and if they are open chamber heads compression is not the problem. After a closer look at the pic's I'm going to say you used the wrong head gasket's . Blocked off the water passage's to the heads , hens 220* and a dropped valve seat.

Ditto everything Jeff said. Plus check the sea pump. Cooling was probably the issue.

Fuel preassure was arround 9 psi.

The exhaust valve seat droped and was pressed into the piston, then disintegrated mostly. The other head , the intake valve seat was also coming loose, hence the drop in compression. The machine shop said all the valves looked ok, nothing else was really wrong except the seats.

the heads are stock 502 heads, im trying to get the casting number to make sure.

Calculate the compression ratio accurately and provide the camshaft specifications advertised, and at .050 lift.

Based on the cc of domes, heads stated (116cc?) and head gaskets I'd estimate a static comrpression of 9.75-10:1. This assumes the deck height at .010".