Yes, these engines received a lot of abuse, but what about all the pampered passenger cars that developed head cracks? Pouring a hundred pounds of molten iron into a fairly primitive sand mold had to be a pretty good challenge with the foundry methods in use 70-something years ago, and the basic design of the stovebolt six engine originated in the 1920s. The head design has to be a factor, just like the design of the cooling system of flathead Ford V8's made them prone to cracking blocks- - - -right across the exhaust valve seats. Finding a 59-A series flathead without cracks to modify for the dirt track got to be quite a challenge, also.
Jerry
