Rocker Arms

[Guest Anonymous]

Ok everyone, question.

 

what's the going "looseness" of rocker arms? When the valve is all the way open, should they "rock" at all or what? I can't figure it out, and right now I have them set at just barely movable under normal hand force. when I run the car a little, and pull the valve covers off, they are all loose again. Thanks for the 411 guys. Oh yeah, I have a chevy 350 with alum heads on it. Thanks again.

sean

[Modern Motorsports Ltd]

looseness can vary from 1/2 to a 3/4 turn past 'snug', with snug being point at which you feel the pushrod resist rotation by your fingers (not point at which you can no longer turn it, with soft hydr. lifters this can be important). Hey is it a hydraulic cam? Typically I go 1/2 turn past snug for the 'cold' (ie. non-running) adjustment. A non higher rpm/non racing setup can go 5/8's or a hair more and run them a bit tighter.

 

THEN, once you've got it up and running etc and want it adjusted dead nuts right, I do a HOT adjustment. Not absolutely necessary but it's led to the quietest valvetrain on all my motors. Cut up some 'spare' valve covers (can be lorise) so the tops are wide open and flared up but still allow access for your wrenches/sockets etc, whatever you use to adjust them. Install one on one side (after engine is warmed up) and proceed to loosen that rocker arm unless you're already positive it's loose (ie. clicking), then slowly tighten until the very moment the 'clicking' (it is audibly distinct) fades out/quits. This is 'snug' as I referred to up top, go 1/2 turn tighter and lock it in. If using locknuts I go 3/8's of a turn and for the last 1/8 I turn the locking set screw snug first then outer 1/8 turn and this gives it a very tight 'lock/set'. Just tightening the set screw afterwards does not I've found.

 

Very satisfying to have a quiet valvetrain you've set hot and know you have them all nailed down. A bit messy but not a big deal, a comp cam or similar (crane) adjusting wrench with inset allen key is quite handy for this. Allows vertical access with minimal oil splash. Oh yeah, if you have stamped rockers you can install (temporarily) metal clips to minimize (they do help) oil spray (Mr. Gasket has some as do others).

 

If you have a solid roller cam then it's a different procedure and you only set them cold as per a different spec....ooops, by cold I meant non-running.....as Pete says, best done hot.

 

I've bent a set of pushrods from excessive revs and learned to appreciate having valves set just right Your idle can really smooth out once they're tuned in as well...pretty kewl as you progress in your adjustments and your idle just keeps smoothing out more and more........

 

good luck

 

[ October 18, 2001: Message edited by: Ross C ]

[pparaska]

Actually, if it's a solid cam, it's better to adjust them hot. But you hav eto be quick as the valve train cools quickly.

[Guest Anonymous]

Yeah, rocker hole restrictor clips should be used as was mentioned and get a old stock valve cover (see there was a reason to save them! ), whack the top off and bolt it on. It keeps the oil from running over and onto the header, this depends on your oil pressure of course.

 

I say this from a bad experience with a AMC my buddy and I were putting it back together. We started it and were working on taking a bit of tick out of the hydraulics by tightening them. An oil fire started between the firewall and the cylinder head. It managed to burn about three hard to get at wires before we got it out. Oil fires are not fun at all, specially if you can't smother the flame. Fire extinguishers can be used, but leave a big ass mess.

 

Anyway, just thought I'd pass that on and maybe keep someone from doing likewise.

 

Regards,

 

Lone