The heads that I had were 184cc intake runners and if I remember correctly the chamber size was 72cc. The car is a 74 nova weighs 3190 with 410 spool in the rear end. I was shifting the car at 6500 rpms. The converter is a 3000 stall The carb is a 750 holley vac seconary. No I don't know that the heads were the problem. Have a good carter elctric fuel pump. Not real sure on what size the headers are. The 60 foot times were 1.7