how fast can we go roundy round

[Black dawg]

I dont think that would be common if we all ran 4500+. I have run lots of ford motors with good spring pressure (400 open 140 closed) and the cam that required them, and never broke one of those bolts. I was always worried about it though. did the pushrod live? any piston/valve contact?

 

[Hyde]

I would have to guess what caused the failure was piston/valve contact due to the floating valves. The bottom picture is the pushrod showing the curve in it. That said I put a new bolt and 2 pushrods in and drove it like that for a long time. Never tore it down to see how extensive the damage was.

With the EGTs I used to run that thing the pistons must have been so soft Im sure the valves just made their own reliefs