mike...
rocker nut difference
Thread Starter
Racer
Joined: Feb 2010
Posts: 371
Likes: 65
From: south wilmington il.
rocker nut difference
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.
Melting Slicks
Joined: Mar 2009
Posts: 3,126
Likes: 15
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...
Thread Starter
Racer
Joined: Feb 2010
Posts: 371
Likes: 65
From: south wilmington il.
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.
Le Mans Master
Joined: Nov 2008
Posts: 5,691
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From: columbus oh
Racer
Joined: Jan 2009
Posts: 261
Likes: 1
From: frederick maryland
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..
Le Mans Master
Joined: Jun 2004
Posts: 6,231
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From: Seattle WA
St. Jude Donor '14
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Race Director
Joined: May 2005
Posts: 10,674
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From: Millington Illinois
St. Jude Donor '08-'09
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.
Safety Car
Joined: Mar 2007
Posts: 3,652
Likes: 49
From: Bridgewater nj
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.
and check your cast numbers. Who knows, you might have two different heads.
Drifting
Joined: Aug 2004
Posts: 1,883
Likes: 124
From: Lubbock TX
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.
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.
Racer
Joined: Jan 2009
Posts: 261
Likes: 1
From: frederick maryland
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.
Melting Slicks
Joined: Oct 2002
Posts: 2,317
Likes: 111
From: St Louis MO
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!
Why not use poly-lock nuts?... Most won't work with normal height stock valve covers!
Race Director
Joined: Nov 2002
Posts: 12,142
Likes: 54
From: Taylor Michigan
thanks for the spelling correction
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........
