I had some rocker arms come loose on me late last year. After going through adjusting all rocker arms, I drive about a mile and the #5 cylinder rocker comes loose again. Readjusted several times, but problem persists. At this point, I know the problem lies somewhere other than a bad adjustment. My first thought is bad lifter.

This is on a 5.7 TPI, 1.52 roller rocker arms with zz9 cam, 5/16 7.2 pushrods, and zz9 valvesprings. The only part that is stock on the valvetrain are the lifters and everything was installed back in '99, so I know it was properly setup. Any thoughts?

 

Not a lifter.

Either you've got a pull-out stud that's doing what we call them that for, or you're not tightening the rockers correctly when you adjust them, and they're backing off by themselves.

 

Hopefully it's something where I don't have to take off the heads.

Anyways, I should have been a little more specific. It's always the #5 exhaust rocker that comes loose. Here is what I do to adjust them: for exhaust valve, I rotate engine until #5 intake pushrod/rocker goes all the way up and let it come back about half way down. Finger tighten the rocker nut, which at this point there is no slack in the pushrod. I then tighten the nut about 3/4 turn and then tighten set screw.

This is a newbie statement, so correct me if I'm wrong: I thought the stud screws into the head. If the pull-out stud did in fact come out, what is the best way to fix that? Use a hammer to "nail" it back in place, or should it screw back in? Thanks.

 

factory studs are press in... they are just pushed into the hole... screw in studs for the most part are after market you have to tap the heads to put them in... did you pull the entire rocker arm off and make sure the stud isnt stripped... it may get tight but after a few hits if its stripped it will just pop right back up... and depending on your setup you can also let the lifters all the way down then adjust the rockers.. just let the springs fully open the lifter seated all the way down and tighten while spinnign the pushrod untill it just stops spinning... but like i said this will all depend on your setup if its solid or hydralic, flat tappet or roller....

 

Sounds like your valve adjustment techniques could be improved a bit.

Try tightening the rocker nut and set screw together. That is, if your favorite preload amount is ¾ turn, try setting it to a little more than ½ turn instead; tighten the set screw as you describe; then put a box wrench on the nut and the allen key on the set screw, and tighten the nut and set screw TOGETHER another 1/8 turn or so. You can probably get the set screw 5 times as tight that way as you can by the key alone, with the same amount of effort. Just don't get so carried away acting like a gorilla on it that you split the PolyLock at the bottom of the set screw. Yes, it happens.

 

Thanks for the advice regarding the valve adjustment. I'll try that and go over all the studs to make sure they aren't popping up a bit (again, what's the best way to put them banck in the correct position?). That may be the case as I noticed visually that the set screw was turned in farther than other set screws in the rocker nuts.

As for the stud itself, it doesn't appear to be stripped. I took the rocker off and could screw the nut all the way down and up without any binding and it doesn't have any shave marks.

 

That would be, by getting rid of the pull-out studs.

If in fact it's pulled out, then banging it back in won't do much; and it will contaminte your oil with antifreeze, because the hole goes RIGHT DIRECTLY INTO the water jacket.

Take both heads to the machine shop, and have them mill down the guide bosses, and drill & tap them for screw-in studs. Never have to worry about it again.