Rocker Adjustments
Thread Starter
Intermediate
Joined: Sep 2005
Posts: 26
Likes: 0
From: Perth Western Australia
Rocker Adjustments
Hi all
I have just changed my valve seals and replaced the rockers. The Haynes Manuals recommends adjusting rockers when the piston is TDC until the push rod can no longer be turned by hand then a futher full turn of the rocker nut. I am a little concerned that this may overtighten the rockers and cause damage. I have read were only a 1/4 or 1/2 addition turn is all that is necessary. Its a standard 85 Vet.
Any suggestions?
Andy
I have just changed my valve seals and replaced the rockers. The Haynes Manuals recommends adjusting rockers when the piston is TDC until the push rod can no longer be turned by hand then a futher full turn of the rocker nut. I am a little concerned that this may overtighten the rockers and cause damage. I have read were only a 1/4 or 1/2 addition turn is all that is necessary. Its a standard 85 Vet.
Any suggestions?
Andy
Le Mans Master
Joined: Aug 2003
Posts: 9,884
Likes: 3
From: Magnolia Mississippi
St. Jude '03-'04-'05-'06-'07
1st: Get a FSM (helms) and use the haynes for a door stop.
2nd: Rockers and adjustments are covered in prior posts many times over, use the search function and your'll get more info than you can imagine...
2nd: Rockers and adjustments are covered in prior posts many times over, use the search function and your'll get more info than you can imagine...
Team Owner
Joined: Dec 2000
Posts: 90,675
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From: SE NY
Cruise-In II Veteran
A fail-safe method is EO/IC:
-select a cylinder
-turn the crank till the Exh valve just starts to open and adjust the Int valve
-turn the crank till the Int valve starts to close and adjust the Exh valve
I set zero lash by twirling the PR and adjusting the rocker nut till I just feel drag. Then I give the nut 5/8 turn more and lock the position. This puts the preload between 1/2 & 3/4 turn past zero lash.
-select a cylinder
-turn the crank till the Exh valve just starts to open and adjust the Int valve
-turn the crank till the Int valve starts to close and adjust the Exh valve
I set zero lash by twirling the PR and adjusting the rocker nut till I just feel drag. Then I give the nut 5/8 turn more and lock the position. This puts the preload between 1/2 & 3/4 turn past zero lash.
Racer
Joined: Feb 2006
Posts: 269
Likes: 0
From: Vancouver B.C.
I agree with Vinnie, do a search if you like reading rather than doing. (Sorry Vinnie, couldn't resist)
However, If i were you I'd 'aproximate' the correct lash then fire it up and adjust all rockers by 'ear'. Then while running I'd 'tighten' each rocker 1/2 turn (exactly) and set your lock.
THEN I'd install the covers and worry about the oil mess.
OR....you can READ how to do it.
However, If i were you I'd 'aproximate' the correct lash then fire it up and adjust all rockers by 'ear'. Then while running I'd 'tighten' each rocker 1/2 turn (exactly) and set your lock.
THEN I'd install the covers and worry about the oil mess.
OR....you can READ how to do it.
Team Owner
Joined: Oct 2004
Posts: 81,241
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From: altered state
St. Jude Donor '05
that pushrod will keep spinning as you crank it down so I wouldnt go that route....I take the up/down slack out of them and then go 1/2-3/4 turn or so and see where youre at.
This place is your online manual.
This place is your online manual.
Race Director
Joined: Jan 2002
Posts: 12,263
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From: O'Fallon Missouri
Team Owner
Joined: Dec 2000
Posts: 90,675
Likes: 304
From: SE NY
Cruise-In II Veteran
I've found that the difference between just beginning to feel a little drag on the PR and it being hard to twirl is about 1/8 turn. That's why I chose 5/8 turn as the set.
This technique requires a sense of touch but it's easy to develope.
This technique requires a sense of touch but it's easy to develope.
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Team Owner
Joined: Dec 2000
Posts: 90,675
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From: SE NY
Cruise-In II Veteran
I saw a mechanic friend of mine bend pieces of cardboard over the PRs of a 4-banger rice-burner to set valve lash and there was no oil spill nor spray, though I don't know how that technique would work on our SBCs??
Drifting
Joined: Dec 2005
Posts: 1,309
Likes: 20
From: Woodstock Georgia
I just set the lash on my new pushrods. The method I used:
1. When the exhaust valve starts to open, set the intake vavle
2. When the intake valve is approx. 3/4 closed, set the exhaust
I tightened until there was no up and down movement, and added 1/2 turn and set the locks.
I tightened my original rockers while she was running...I cut a small strip of cardboard to deflect any oil from getting on the headers. There really wasn't much of a mess at all. But the exhaust was so loud that I had a hard time locating those that needed the lash adjusted.
1. When the exhaust valve starts to open, set the intake vavle
2. When the intake valve is approx. 3/4 closed, set the exhaust
I tightened until there was no up and down movement, and added 1/2 turn and set the locks.
I tightened my original rockers while she was running...I cut a small strip of cardboard to deflect any oil from getting on the headers. There really wasn't much of a mess at all. But the exhaust was so loud that I had a hard time locating those that needed the lash adjusted.
Melting Slicks
Joined: Apr 2002
Posts: 2,118
Likes: 0
From: St. Charles, MO Route 66 Corvette Club
NAPA sells some little spring clips that prevent the oil from squirting out of the rocker arms. They cost about $6.00.
Just curious as to why the 5/8 turn is used when the FSM indicates one full turn beyone the zero lash. Trying to learn something here!
Just curious as to why the 5/8 turn is used when the FSM indicates one full turn beyone the zero lash. Trying to learn something here!
Racer
Joined: Apr 2004
Posts: 378
Likes: 1
From: Fremont NH
I just picked up a set of 16 of those little clips you mentioned..
I should be firing up my project on Saturday and will be adjusting my valves while the car is running.. seems like the best way to do it.
You can set by the book without the car running, but if the lifters have collapsed a little, whats the point?
I learned a valuable lesson while doing my intake gaskets (and a million other things 'while I was in there') when I tightened my rockers to get rid of the play they had.. none took more than 1/2 turn.. but then, the next day, they had play again.
I'm backing them all off 1 full turn then once the car is running with the clips in place I'll back them off more if needed to get each one clacking.. then I'll tighten from there.
Can't see how that method wouldn't work the best.. and with the clips stopping the oil spray, seems like the way to go.
I should be firing up my project on Saturday and will be adjusting my valves while the car is running.. seems like the best way to do it.
You can set by the book without the car running, but if the lifters have collapsed a little, whats the point?
I learned a valuable lesson while doing my intake gaskets (and a million other things 'while I was in there') when I tightened my rockers to get rid of the play they had.. none took more than 1/2 turn.. but then, the next day, they had play again.
I'm backing them all off 1 full turn then once the car is running with the clips in place I'll back them off more if needed to get each one clacking.. then I'll tighten from there.
Can't see how that method wouldn't work the best.. and with the clips stopping the oil spray, seems like the way to go.
Race Director
Joined: Dec 2002
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From: SCMR Rat Pack'r Charter Member..Great Bend KS
(I know; it's a geometry thing...)Best advice I could give: Go by the manual for YOUR car.
Larry
code5coupe
__________
i ain't easily impressed....
Le Mans Master
Joined: Oct 2003
Posts: 6,130
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From: seattle WA
I'm also of the old school, and I've used the little clips for years. 
with vinnies87..do a search, and you'll learn how to basically adjust all lifters CLOSE before starting the engine. One of the main things you don't want to do is over tighten them..that can cause engine damage. The reason guys have found a difference on how far they need to adjust is simple, maintainance...even though we're talking same basic 350 some engines will experience more wear on the valve train (ie. cam, lifters,rockers) if they've been somewhat neglected....prolonged oil changes etc.So, just don't over tighten.
Before I get flamed, thought I better add, other than maintenance, mileage and how hard an engine has been beat also contribute to wear.
with vinnies87..do a search, and you'll learn how to basically adjust all lifters CLOSE before starting the engine. One of the main things you don't want to do is over tighten them..that can cause engine damage. The reason guys have found a difference on how far they need to adjust is simple, maintainance...even though we're talking same basic 350 some engines will experience more wear on the valve train (ie. cam, lifters,rockers) if they've been somewhat neglected....prolonged oil changes etc.So, just don't over tighten.Before I get flamed, thought I better add, other than maintenance, mileage and how hard an engine has been beat also contribute to wear.
Last edited by rick lambert; Apr 27, 2007 at 11:29 AM.
Race Director
Joined: Dec 2002
Posts: 13,348
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From: SCMR Rat Pack'r Charter Member..Great Bend KS
Melting Slicks
Joined: Jun 1999
Posts: 2,949
Likes: 23
From: Bowling Green KY
I've never done the running adjustment but had bought some cheap valve covers and was gonna modify em' to try the running method but I'm gonna get some of these!
This place is great . . . .
Team Owner
Joined: Feb 2006
Posts: 24,460
Likes: 7
From: sw Ohio
Here's the safest advice, pay a reliable mechanic to do it. I've tried to do it myself probaby 40-50 times with unsatisfactory results. I've tried using special tools to find TDC and they just dont work on an L98. So I think the best thing to do is pay the mechanic to do it or if your lucky enough, maybe he'll show you how.
Team Owner
Joined: Feb 2006
Posts: 24,460
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From: sw Ohio