I have a SBC 400 engine with Edelbrock RPM Aluminum heads,Comp Cams Hyd cam(.469" lift),Comp Cams 1.6 Magnum roller rockers with polylocks,about every 4-6 months a couple of rocker arms will come loose and I will have to readjust them,I get 0 lash on them and tighten to about a quarter turn after 0 lash,do I need to tighten them to about half a turn or what,ANY HELP?THANKS
Rocker Arms Keep Getting Loose ????"s
- Thread starter dickeymoore
- Start date
Uh-oh. What oil do you use? What's its API rating, do you use any 'ZDDP' type additive during oil changes?
See here for the potentially bad news:
See here for the potentially bad news:
Last edited by a moderator:
I've had problems with poly locks over the years. If it tightens back to where it was then thats the problem. If not then you have more serious problems.
I've always tightened the poly lock then give just a snug on the adjustment nut. But like stated earlier what kind of oil are ou using and any zddp?
What other problem can it be or do I need to go with a half turn after 0 lash instead of a quarter turn or what?THANKS
What they are getting at is, if the oil doesn't have the right API rating the cam will wear prematurely.
On the adjustment, I run the nut down to zero lash then snug the lock then tighten the nut 1/4 turn.
On the adjustment, I run the nut down to zero lash then snug the lock then tighten the nut 1/4 turn.
Looking from a assembly standpoint first, if the studs are junk, the set screw will not have a flat surface to jam against. This is important. And as was said, the correct way to set the lash is to tighten the poly lock nut to CLOSE to where you want the lash to be. Then tighten the set screw. Now tighten the poly lock nut to where it has to be. On a hydraulic, I move the pushrod up and down until there is just no slack. Then I put a white dot on the nut. I go for 1/2 turn with aluminum heads for expansion. So I turn it almost 1/2 turn, like between 5 and 6 oclock. Then set the set screw and tighten the poly lock to 6. This has never failed. However, I use ARP studs in the heads with machined ends so the set screw makes full contact on the stud. Otherwise you wear down high spots and the poly lock loosens.
The important question is, are the adjusters coming loose, or does it just keep creating lash that wasn't there before? If it's eating cam lobes, more preload will just postpone the time until it gets loose and starts ticking again.
