Originally Posted by 1932bantam
good luck with those heads. i would be using a stud girdle also , I had same problem I removed a little of the heads so sparkplug would clear. with a .640 lift flat tappet no girdle broke the stud boss out of the head the casting looks very porus on the inside and these heads are around 5lbs lighter than any other al. head. Just fired mine up today with a set of steel 188's no more procomp for me . there combustion chamber is different than stock is why you hit.
we are using a stud girdle it is recommended to use one with my cam, The castings were the only part or the pro comp heads he was ok with using he also said the assembly was very poor and would not have worked with even a smaller cam. I would never buy another set I traded a better set of heads for them I had a set of 69 427/454 rectangle port aluminum heads that needed valves I traded for this set