Classic/Antique Car Repair: Pontiac rocker arm adjustment, 68 firebird, pontiac engines

Question
I have a '68 firebird 350 which sat for 10 years.  I replaced the all of the push rods and lifters because two of the lifters were plugged and no longer worked. I have adjusted the hydrolic lifters but the nuts on some of the lifters keep coming loose and they begin to chadder.  Is this a common problem whenever you reuse the original rocker arms and nuts?  If so, can I get new standard nuts or will I have to upgrade to poly locking?  

Answer
Some Pontiac engines used screw in studs (the rods that hold the rocker arms down) and some used press in studs - and your 68 could have either one.  If they are screw in studs, they may be backing out on you. It is possible to take them out and clean the mating surfaces with powerful drying solvent like brake cleaner, then using a "theadlocker" type sealant, reinstall them.  You will probably have to file a slot in the top of each stud so you can remove and reinstall them.   

Your engine might have pressed in studs - there is no way to tell for sure without pulling one of them out to look. If you pick one of the ones that keeps loosening on you, just keep tightening the rocker adjustment to see if you can get it to pull all the way out.  If you can, you can try pressing it back in again, using a "Lock-Tite" product to keep it from pulling out again.  You'll have to clean it up the same as the screw-in type to get a good strong bond with the "Lock-Tite".   I guess you could tap the tips with a hammer to seat the press-in stud, it might work, but you are probably going to have to take the heads to a machine shop to get this done professionally with a hydraulic press.  You can't risk messing up the tip of the stud, else you wouldn't be able to adjust the lifter clearance.

These are a pain in the butt - a bad design that has bugged people for years!

Of course it is also possible that the top nuts are backing up on you too - but I doubt it. Just to make sure, pay attention to the position of the flats on one of the nuts that loosens to see if it is turning after you adjust it - maybe take a good picture showing all the nuts positions, then drive the car until you hear the clicking again, then compare the nut positions.  Of course if you have screw in studs, you still don't know which end is loosening - if the stud unwinds out of the block, the nut will move too - so also mark the tip of the stud to see if it is turning.

Dick