hello,
I have afr heads with screw-in rocker studs, guideplates and comp cams magnum roller rockers (1.6 ratio). My problem is this: we put everything together two weeks ago and had some tuning issues, which we worked out and I was able to drive the car for one night. The valvetrain was a bit noisy so we did another valvle lash adjustment and the next day we had a very noisy valvetrain and a bent pushrod. We evidently forgot to tighten the allen bolt on intake 1 and 3, exhaust 3 and he pushrod came out of the lifter and went down into the lifter valley. Replaced bent pushrod, performed another valve lash adjustment. 20 min of runtime later, intake 4 was loose tightened that up and checked the others. They were fine. started it back up, and it was perfectly quiet! I thought we had it fixed for good. But now it is beginning to get noisy again. Do I have to put loctite on the threads or something? They keep backing off! Any ideas?
Thanks,
John

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• 84 Firebird w/ T/A gfx
• 350 4bbl (LM1)
• Automatic
• Non-leaking T-Tops (new rubber all around)
• Working headlights (new parts)

Mods: 14" K&N open element, 160* stat, ram-air hood, Accel cap & rotor, MSD Super Conductor Wires, 24mm solid rear & 36mm hollow front sway bar w/ PST polygraphite bushings & endlinks, Spohn SFCs, WS6 springs, SLP 1 3/4" Jet-hot coated headers, Hooker 3" cat-back, Catco high-flow cat, Comp Cams High Energy 268 cam, AFR 190 heads, Weiand Action+ intake, Comp Pro Magnum 1.6:1 Steel Roller Rockers, Moroso Oil Pan with trap doors, windage tray and crankshaft scraper, poly graphite motor mounts, K&N oil filter and Mobil 1 synthetic.

http://www.homepagez.com/350thirdgen/

 

When you tighten them, you should do the last 1/16 turn or so of the allen screw by turning the nut along with it at the same time... there's like no way in Hades you're going to get that Allen tight enough to be effective by itself.

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"So many Mustangs, so little time..."
ICON Motorsports

 

Dude, I must be a mind reader. I was doing exactly that when I took a break to see if anyone responded. I did the first set (with #1 TDC) and now I'm going to go do the second set that way. Thanks man!
John

 

I finnished the other set and drove it. It seems OK for now, but who know how long that'll last. I have to drive it 30 miles to school and then 30 miles back tomorrow, and I don't feel like having them come loose again while I'm away from home. Somebody my dad talked to said something about "poly locks" or something. I guess they're kind of like those hex nuts with nylon in them to keep them on the threads. Has anyone heard of these?

 

After you use a 9/16 or whatever size socket to tighten them to the correct lash you then need and allen wrench to stick in the hole in the center and tighten the inside bolt.
Did you do this

 

Poly Locks are what you've got, with the Allen set screw in the middle. A common trade name for the kind with the plastic insert in Nylock. They won't work there because of the heat that exists there.

I have had to use jam nuts before on some of the regular style lock nuts.

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"So many Mustangs, so little time..."
ICON Motorsports

 

if they continue to change, it normally comes down to incorrect geometery. The lash won't remain consistent if the geometery is causing something to wear abnormally.

good luck, your in good hands with RB.

 

I had a set of "poly locks" on my BBC and I couldn't keep them tight, no matter what I tried.

I traded a guy those for a stock set of rocker nuts (I hated those things) and never had a problem again.

I will never run another set.

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ASE Mechanic/Machinist/Smog Tech

1999 NBM Trans Am
1986 Chevy 3/4 ton pick up
1981 corvette
1995 Kawi ZX6R
and 2 POS commuters...

R.I.P. #3
"He can see air"

 

Aaron, yeah I tightened them. It seems to me that these poly locks only prevent the hex nut part from moving down on the stud not back off of it. Should I try my old rocker nuts from the stamped steel stock ones? Why they hell did comp cams even send me these pieces of junk? I am starting to believe my pushrods are not the correct length, also. The wear pattern on the valve stem tip is too wide according to lingenfelter. Thanks for sharing your ideas and experiences guys.
John

 

you mentioned your cam and 1.6 ratio rockers, and heads did you happen to get new lifters? your lifters may be bad, and they are collapsing, i just went through this, adjusted the rockers, 10 minutes of idling and tick tick tick again.

 

Your valvetrain is on the verge of binding somewhere, abosutely guaranteed.

The giveaway is the bent pushrod.

Tighten things up all you want, use whatever locks you can lay your hands on, it's not the problem. You're binding up somewhere- like the rocker arm is running out of travel or the retainer is hitting the valve guide at max lift.

#1 offender: pushrods that are too long. Buy a MrGasket pushrod length checker and use it.

Don't say you haven't been warned.

 

The lifters are new, thanks for the idea though. The pushrod bent because the rocker arm rattled loose and the pushrod came out of the lifter and/or rocker arm niche, but you're right the valvetrain geometry was off (which caused the problem). I checked the pushrods with an adjustable one and they are too short. I need stock + .100" pushrods as I found out today and ordered them. Will these poly locks work to maintain valve lash now if I tighten them as recommended above? I guess I will answer my own question in a few days when the pushrods get here. Thanks to you all.
John