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Old 11-25-2008, 06:35 AM
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Rocker Arm Adjusting Nuts Problems - Help Me Diagnose

Guys:

I made a few posts earlier this week about problems I had with a rocker arm falling off of my BBC because the adjusting nut broke in half. I discovered yesterday that many of the adjusting nuts are showing "wear" and have been damaged at the bottom of the nut - where it contacts the rocker. Eventually more of them would have failed.

This is obviously the cause of the failed nut that broke in half and left the rocker to pop off the stud.

So there are "issues" going on here. I put in a new roller cam, push rods, and valve springs last winter. The new cam has higher lift (.650") because it's a roller. I reused the rockers and nuts. The new valve springs are much stronger, but not "crazy" strong.

I'm thinking I had the incorrect adjusting nuts for my rockers. I need your help to diagnose this problem.

Here's the setup for my 468 BBC

1) Comp cams 11-771-8 roller cam (billet core) (.650 lift)
2) crane energizer rockers (1.7)
3) adjusting nuts (not sure what size they are)
4) comp cams valve springs (954's)
5) comp cams 3/8 magnum push rods
6) 7/16 X 24 rocker studs (ARP)

any help would be appreciated.

Lee

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Old 11-25-2008, 08:22 AM
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could this be caused by not having enough valve spring clearance between the spring coils? Possibly the spring is fully compressed and the cam lobe still is pushing for more lift?

Thing is I checked all that when I did this build. I checked installed spring height, vs valve lift, etc. Also checked coil bind clearances at installed height. Thought I had enough clearance there.

Maybe this is a valve spring coil bind issue?

Help.........
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Old 11-25-2008, 08:42 AM
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Quote:
Originally Posted by leejoy
could this be caused by not having enough valve spring clearance between the spring coils? Possibly the spring is fully compressed and the cam lobe still is pushing for more lift?

Thing is I checked all that when I did this build. I checked installed spring height, vs valve lift, etc. Also checked coil bind clearances at installed height. Thought I had enough clearance there.

Maybe this is a valve spring coil bind issue?

Help.........

If that was the case i personally would think you would be bending push rods.
I also assume you have posi-lock nuts....Are you sure the trunion of the rocker is not flopped upside down as you install the rocker arms? One side of the trunion should be machined for the rocker arm nut the other side will not be...

Last edited by HalfOunce; 11-25-2008 at 08:45 AM. Reason: additional question
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Old 11-25-2008, 08:49 AM
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Quote:
Originally Posted by HalfOunce
If that was the case i personally would think you would be bending push rods.
I also assume you have posi-lock nuts....Are you sure the trunion of the rocker is not flopped upside down as you install the rocker arms? One side of the trunion should be machined for the rocker arm nut the other side will not be...
No I am not sure. That's probably the problem. If what you say is correct, I probably have the trunnions installed upside down on many of them. I'll look at it when I get home - I don't recall if those rockers are made like you described. Are all rockers made such that one side of the trunnion faces down and the other side faces up?
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Old 11-25-2008, 08:51 AM
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Most of the full roller rockers i have seen are made that way yes.. ill see if i can find pix. The trunions just spin within the rocker arm..
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Old 11-25-2008, 05:05 PM
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The flat side of the trunnion will be facing up when installed correctly so the adjusting nut will sit flat against it. The other side is coned and it goes down into the rocker arm.
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Old 11-25-2008, 10:25 PM
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I have seen them break if the stud is too long. So if you can only get the allen head in there a few threads this may be your problem.
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Old 11-26-2008, 05:51 AM
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Try "tool steel" nuts and washers. They will not break. Manton has them and is the source for many companies.

PS: If you are a Chevy guy be sitting down when they give you the price, I AM USED TO IT...(see name)
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Old 11-26-2008, 06:14 AM
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If the nuts have a set screw to lock it down maybe you're putting that too tight. Does the ball fit the rocker properly? Are you putting the nuts on backward?

I think I remember reading about people breaking these before, maybe do a search on it?
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