I see the casting number on one head - looks like ---4480, find the casting number from the other head. You can then determine the chamber volume and factory valve size. There is a good chance the valves will probably be the same size but the chamber could be different if the castings are of different years or hp output. I built a 383 with heads of the same casting number but different years, I c.c.'d the heads and found one with about 2 c.c.'s higher volume so I had one of them milled to match the other chamber volume.
Apparently the power pack heads have a 58cc chamber volume. I searched Speedway Motors just for kicks. They only listed 64cc heads. That would reduce compression and performance. Do I need to pull these heads to measure volume?
