H-I-J '76 Nova re-fit.

[Nmbr1GMfan]

Originally Posted by Rich Biebel

I’ve never seen or used those pin locks.

My own engine in my dragster has Diamond pistons and spiral locks the std. used for many years. Single or double and I’ve never had one break or come out.

It was s.o.p. to verify the pins had some clearance or movement between the locks. Every piston I assemble, I check to be sure the pin can rotate freely in the piston without binding on the locks.

Obviously something way wrong with the lock, piston, pin arrangement.

That was a real bad mess and should not have happened given they were all good name brand parts.

Years ago we used a snap ring type pin lock. Spiral locks became the normal lock usually used. The locks tend to dig into the groove and raise up a burr but unless they were not installed right, rarely failed.

Very ugly mess. I’ve seen plenty of blown up engines. It’s never pretty and always expensive.

Sorry to see it ....

Rich, these Diamond pistons were built for a snap ring style (from Diamond) and had the corresponding pin for the snap ring style lock (they're different).