Motor started ticking today and I knew is was rocker releated. Pulled the cover and found a 7/16" Comp poly-lock broke in half which allowed the rocker to make the ticking sound. No signs of the rocker striking the body either.

Anyone run into Comp poly-lock failures?
Are ARP poly-locks better quality?

 

you tightened it too much, I see people break them all the time bc of that.

your at fault!!

 

Whats the correct way to tighten them then?
FTR I torque the set screws to 25 ft pounds.

 

Adjust the preload just shy of where you want it. Run the set screw down and snug it up against the stud (nothing crazy just snug). Then tighten the hex of the polylock while keeping a bit of tension on the set screw. Usually for me its about 1/16 of a turn or less when tightening down the lock. I just do it by feel, haven't broken one yet (don't use a long wrench if you're a tough guy). Still no need to go crazy with it, if you do it right its not coming off unless you take it off, period.

Same thing goes for taking them off just put the wrench on the hex part and screw em off.

If you're leaving bad scars on the top of the studs you're overdoing it.

 

25 ft lbs seems like a lot for that tiny little screw. Also, if you do the thing of setting the screw and over-tightening the big nut more-that's another way to break them.

 

The trick to having them tight enough so that they wont loosen over time is in the stud itself. A good stud will be flat and square where the set screw sits. This will ensure even pressure across the bottom of the set screw. If you have quality studs, cranking on the poly's is not needed.

The method I use is to hold the poly with a wrench at the preload that I need, then use a hand held allen, either a "key" or a Tee style, and tighten untill the tool flexes. It acts kinda like a torque wrench. Using a socket style allen driven by a ratchet has little to no flex or twist, its easy to over tighten and crack the poly.

Is 25 ft lbs the recommended torque spec?

 

How long has it been/how many miles since you last installed or adjusted the rockers?

That's got me worried, I didn't use anything except my hands and the little allen wrench itself on the set screw and tightened it pretty tight with a wrench on the nut so it wouldn't turn, because I had one rocker slip off the pushrod during adjustment on the other side, so I went back and tightened them all good.

 

I set my pre-load and tighten the set screw LAST. Never had a problem..

 

FWIW, ARP recommends 22 ft./lbs. on the set screw for their polylocks....

 

Me neither, in close to 30 years of setting poly-locks using that method.

 

Then 25 is too much, eh?

Same, here.

 

I've never had a problem with them, but did recently see a friends ls1 with pro mags break the poly lock, and it hadn't been touched in quite a while. Comp sent him a new one for free.

 

Sure looks that way....

 

Interesting. My polylock broke on my ls1 2 weeks ago. Rocker was completely off and kept the exhaust valve shut. I had just got done making a little test run on the spray...thought for sure I lost the motor by the sound of it. I called comp up and told them what happend and they kinda blew it off and was like ok here comes a new one in the mail. I am glad they took care of me but it seems like they were already aware of the failures with them....

 

Update.
I went back and re-lashed all the valves. There were a couple that wre very close to zero lash and clearly were chattering. I torqued the set screws to 20# after lashing the rockers to 1/2 TPZL as opposed to 1/4 TPZL like I did previously. As a welcomed bonus, the rockers are much quieter now too.

The tops of my studs definitely have indentation from the (not flat on the bottom) set screws. The have a sharp ring that is naturally going to dig in a little the way I see it.

It also appears, at least by mesuring the busted poly-lock and referring to ARP specs, there is not a perma-lock that will properly fit the pro-mag. Maybe someone will chime in if I am wrong.

Just need to drive it to se if they will hold.

 

Thats a good thing, If you can see the full "circle" on top of the stud that means it was flat enough for the set screw to sit square on the stud.

I remember reading that ARP polys don't play well with Comp rockers, but that was years ago. Maybe get in touch with ARP and see what they have to say about it.