Adjusting valve lash while engine running?
Thread Starter
Instructor
Joined: Jul 2003
Posts: 217
Likes: 1
From: Atlanta GA
Adjusting valve lash while engine running?
I just finished rebuilding my '93 LT-1 and I have one rocker that is ticking a little bit. The good news is that it is on the right side, so I don't have to take the Alt and A/C off to get at it.
My question is, can I run the engine with the valve cover off so that I can find the the noisey rocker, or will I get oil all over the place?
I know the sounds like a novice question, but I am a novice.
Thanks.
My question is, can I run the engine with the valve cover off so that I can find the the noisey rocker, or will I get oil all over the place?
I know the sounds like a novice question, but I am a novice.
Thanks.
Team Owner
Joined: Mar 2001
Posts: 30,845
Likes: 293
From: Boston, Dallas, Detroit, SoCal, back to Boston MA
I've done it before, and yes it get's messy
If you have an old set of valve covers you can cut the top off, or better yet access holes with the centerbolts, it's a lot better.
They make 2 piece valve covers just for doing this.
If you have an old set of valve covers you can cut the top off, or better yet access holes with the centerbolts, it's a lot better.
They make 2 piece valve covers just for doing this.
Le Mans Master
Joined: May 2006
Posts: 9,226
Likes: 9
From: Irvine Ca
I'm not sure as I've not done it in a while (try 30 years) but there are clips you get that fit onto the rocker and they semi plug the hole.
Back in the day you would tighten the rocker until you heard the tick stop and then back off a 1/4 turn.....warm...You'd get an oil bath unless you had those clips.
Back in the day you would tighten the rocker until you heard the tick stop and then back off a 1/4 turn.....warm...You'd get an oil bath unless you had those clips.
Melting Slicks
Joined: Nov 2005
Posts: 2,736
Likes: 0
From: WAY UPSTATE NY
I'm not sure as I've not done it in a while (try 30 years) but there are clips you get that fit onto the rocker and they semi plug the hole.
Back in the day you would tighten the rocker until you heard the tick stop and then back off a 1/4 turn.....warm...You'd get an oil bath unless you had those clips.
Back in the day you would tighten the rocker until you heard the tick stop and then back off a 1/4 turn.....warm...You'd get an oil bath unless you had those clips.
Le Mans Master
Joined: May 2006
Posts: 9,226
Likes: 9
From: Irvine Ca
You give me way too much credit.......I'm telling you, it's been a few decades....I may be wrong....LOL
Thanks for the clarification. I need a better memory or I can just rely on guys like you to keep me straight.
Do they still sell the clips I saw back then??
Thanks for the clarification. I need a better memory or I can just rely on guys like you to keep me straight.
Do they still sell the clips I saw back then??
Melting Slicks
Joined: Nov 2005
Posts: 2,736
Likes: 0
From: WAY UPSTATE NY
Hey,I'm old too and definatly can't remember what I had for Breakfast 
Pretty sure those clips are still available for stamped rockers.Probably have for rollers too. I think I've seen them at Pep Boy under the Lisle name
Pretty sure those clips are still available for stamped rockers.Probably have for rollers too. I think I've seen them at Pep Boy under the Lisle name
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Drifting
Joined: Feb 2003
Posts: 1,614
Likes: 163
From: Davis CA
If you can set lash with the engine running, I think that you will prefer doing it that way from then on because it is very clear when you hit zero lash -- and then tighten 1/2 turn further. I have always wondered how you can be sure that the hydraulic lifter was "pumped-up" if you did the adjustment with the engine cold -- especially days, weeks or months cold.
My guess is that you will find it so accurate that you will redo your current settings just in case.
I don't believe that a two piece valve cover will work for you because yours are centerbolt.
I have a perimeter set but you could use the same strategy. I bought a cheap set of chrome covers at Kragen and made cutouts in order to access the nuts. For me, that meant cutting the top off. You would have to be more selective. You can also find a spare set, a press metal set, from another chevy engine.
My guess is that you will find it so accurate that you will redo your current settings just in case.
I don't believe that a two piece valve cover will work for you because yours are centerbolt.
I have a perimeter set but you could use the same strategy. I bought a cheap set of chrome covers at Kragen and made cutouts in order to access the nuts. For me, that meant cutting the top off. You would have to be more selective. You can also find a spare set, a press metal set, from another chevy engine.
Race Director
Joined: Jan 2005
Posts: 10,641
Likes: 13
From: Slidell Louisiana
When I'm setting my preload with engine hot I don't use a cut valvecover.... I lay a rag over the rockers I'm not actively adjusting and don't rev it/ I haven't had oil on the headers yet. Simply uncover rocker loosen until its tapping then tighten how ever many flats you combo requires.....
MIke
MIke
Pro
Joined: Mar 2008
Posts: 579
Likes: 2
From: High Bridge New Jersey
It's
I just finished rebuilding my '93 LT-1 and I have one rocker that is ticking a little bit. The good news is that it is on the right side, so I don't have to take the Alt and A/C off to get at it.
My question is, can I run the engine with the valve cover off so that I can find the the noisey rocker, or will I get oil all over the place?
I know the sounds like a novice question, but I am a novice.
Thanks.
My question is, can I run the engine with the valve cover off so that I can find the the noisey rocker, or will I get oil all over the place?
I know the sounds like a novice question, but I am a novice.
Thanks.
You probably already know the adjustment process, but it does involve backing off the lifter until it's noisy, then slowly tightening until the noise stops, then go an additional 1/2 turn.
Good luck.
