spiral or ring type piston pin retainers

[Nmbr1GMfan]

Originally Posted by Rich Biebel

Todd I don't know the exact reason for your engine failure but I would not change what has worked successfully for many years.

I have no idea why a piston company would change to something different.....

I've used spiral locks as I said for many years and the pins don't have a lot of movement side to side between the locks. Never had one come out....

I always make sure the pin is free to move back and forth between the locks after assembly and use a heavier type assembly oil on the pins and pistons....

Round wire locks might work fine but you won't find them in my engine. Now that I know these are out there I would make sure any pistons I buy have Spiral lock grooves and locks.....or I'm not buying them...

My dragster engine is a 565 and has Diamond pistons with spiral locks....I built it......It's 6 years old and has hundreds of runs on it.....and has been apart for inspection and some fresh parts.

I built engines for myself and many others for years and years......

Rich, I agree with everything you've said. Why the piston manufacturers have gone to a round wire lock I can't comment on, I just don't know. What I do know is a round wire lock will not work if the piston manufacturer doesn't machine the groove properly. Not sure if the same applies to a spirolox groove or that type of lock is more forgiving to machining discrepancies.