Originally posted by 4 Jaw Chuck
I just thought of another reason why this might be part of your problem RAW, if the cap releases all the pressure not only do you lose half the cooling capacity and efficiency from the pressurization of the system but the areas that are really hot turn the coolant instantly to steam, certainly would explain the cracked iron your seeing. We never had this problem with the rotary's because there's no head to crack, it just wipes out the rotor seals after 10 races and flakes off a chunk which wipes out the rotor and cases too.
Yeah, I really loved that one.
If I get a chance Ill go out next weekend and take a pic of the radiator Im speaking of, My cousin bought the car from me and he has installed a 12.0:1 351C (with Iron 4v heads) with no cooling problems..