merc49

im rebuilding a 75 350 and noticed i have two different styles of rocker nuts.i have 8 of each but dont know which ones are exhaust and which are intake.8 are regular locknuts and 8 have a small lip on them.there must be a difference but havent been able to find out anything.they both tighten down the same.just want to put them back right so i dont have any problems.if anyone knows please let me know.thanks.

mds3013

Small block rocker nuts come in two different versions that I have seen. One has a smooth rounded top, the other has a squared top with a raised "collar". My '77 had the rounded top on all studs. Some aftermarket nuts have the rasied collar. No distinction whether exhaust or intake that I know of. They all are lock nuts that will have three indentions on the side/top that keep them from loosening. Hope this helps. mike...

merc49

my engine has never been taken apart untill now and am curious why gm put the different nuts on the rockers,a friend of mine said the raised collar ones go on the exhaust rockers but hes not 100 percent sure.

mds3013

Wait and see what the real experts have to say. I am just relating what little I think I know. mike...

midyearvette

makes no difference where they are used and the lock nuts come in several styles....as to why you have 8 of one and 8 of another, who knows??......

learje

id recomend ditchin them and goin w posilocks. no engine guy here, but in other applications often locknuts are only used once. i had a couple work loose after adjusting my valves awhile back. was a PITA doin it all over again for the cost of the posilocks. i do wonder if GM provided any guidance or any engine builders have any recomendations on how often these nuts can be reused..

billla

Ironcross

the smart action to take is to go to your local parts store and buy new ones......who knows how many times they have been used and reused......about Posi locks, they suck...period...

TimAT

And there are a bunch of rocker covers that posilocks won't fit under without modding the cover or going to a tall cover.

63mako

Possible someone changed to 1.6 rockers on the exhaust side. The old single pattern cams and stock heads liked the extra lift and this was a real common mod back in the day to pull a little extra power out of a stock engine. Check your rockers closely. Don't want to mix them up.

hugie82

and check your cast numbers. Who knows, you might have two different heads.

L88Plus

What's a posi-lock? I know about poly locks, never heard of posi locks.
If it's poly locks you're talking about, there's really no need for 'em on a stock engine.
And if they're done correctly, they'll out hold anything out there. Just gotta take the time to learn how to correctly lock 'em down. I've run several sets and have NEVER had one loosen up on it's own.

learje

my bad, looks like they are called poly locks. been almost a year since i installed mine after having a couple rocker nuts loosen. bought them from a local machine shop and havent had any problems since. new stock nuts probably woulda been fine as well.

larrywalk

Self-locking rocker nuts will lose some of their locking ability the more times they've been cycled on and off. If any of them feel looser than the others, they can gradually creep loose over time and increase valve lash (solids) or decrease pre-load (hydraulics). If any are looser, it might be good to replace them all, but also examine the studs too because the threads on the rocker studs can also wear from the self-locking nuts.

Why not use poly-lock nuts?... Most won't work with normal height stock valve covers!

Ironcross

well now ya no...... lern sumptin evry da.....aye

never thought that 'poly' was appropriate for them...don't know why but it always reminded me of something plastic or chemical rather than performance........