Well i put a used set of Comp Pro Mags on my engine and when the builder at the shop went to install them one of the rocker nuts snapped in half. I know they dont require much of torqing down which is odd that one would snap right? The builder said it was really bizarre and said he never really see's these doing this. Question is does this happen more then we think and better off getting a new set just to be on the safe side then sorry later and engine goes boom?

 

The trunion of the rocker is machined on ONE side to accept the poly lock machined in "step",...if the trunion is turn the other side up(the unmachined side) then the mating surface becomes very sharp rather than completely circular,....
something to check?

Something I caught recently rebuilding a LT1 that came with ProMags from another owner, ie. no installation instructions.

 

It was probably cracked and when the builder went to torque the lock it snapped. Not common at all. Who knows how old they are. It's possible the locks were over torqued many times causing fatigue. I'd check all of them. Probably even replace them. They are not that expensive.

 

i have had this happen on two separate engines. i don't know if its just i dont know my own strength or they dont need to be that tight. but i have had them back off too..

 

I recently had a Comp poly lock break in half with the motor running. no harm done except for some ticking. At that time I was torqueing the set screws to 35# which appears to be a bit too much. Now torque them to 25# and that seems to be working well.

 

I have also heard that the ARPs 300-8245 poly-locks are better than the Comps at resisting brekage.

I am going to get a set of these soon.

 

The problem is there junk,my new set I installed did the same thing. I called Comp and they said they were over heat treated and that happened sometimes.They thought it was'nt a big deal and told me to replace them with new,I did but with a better brand. That was four years ago and no problems since.Some batches were ok and some were not.If you have them I would check them often.

 

I think im going to go this route instead of going back to using a Comp set and have it happen again. I know ARP hardwear is top notch and it throwout my engine so might aswell hoy go for it.

Thanks

 

I've used the ARPs also, and if I remember correctly, they call for 22 ft/lbs, so you're in the ball park.

I think what "TIImuch" said has some merit....something to check out.