Would this work for adjusting valves?
Thread Starter
Racer
Joined: Sep 2001
Posts: 266
Likes: 7
From: Sumner WA
Would this work for adjusting valves?
While I was in the process of replacing my valve seals I compressed the cylinders with air. Before I loosened the rocker I decided to tighten it a bit more to see how far I'd have to go before air started escaping past the valve. It only took about an 1/8th of a turn before I could hear air through the exhaust or intake. That made me think maybe that's another way to adjust the valves. Put air in the cylinder then tighten the rocker until air just starts to escape, then back off an 1/8th turn.
Would that work, or am I asking for trouble?
I tried the way it's supposed to be done by tightening until there isn't any up and down movement on the push rod and then 1/2 turn more. The problem is that when I did that, air was blowing past the valve which I assume means I had it too tight.
I'd also try the adjusting while its running method, but that means I'd have to put everything back together (A/C compressor, alternator bracket, etc) adjust the valves running, take it back apart, put the valve covers on, put everything back together again. Maybe I'm just lazy.
Ron
Would that work, or am I asking for trouble?
I tried the way it's supposed to be done by tightening until there isn't any up and down movement on the push rod and then 1/2 turn more. The problem is that when I did that, air was blowing past the valve which I assume means I had it too tight.
I'd also try the adjusting while its running method, but that means I'd have to put everything back together (A/C compressor, alternator bracket, etc) adjust the valves running, take it back apart, put the valve covers on, put everything back together again. Maybe I'm just lazy.
Ron
Team Owner
Joined: Dec 2000
Posts: 90,675
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From: SE NY
Cruise-In II Veteran
The valve may be closed with no rocker installed but how do you know if the pushrod is on the cam base circle or on a lobe??
When setting lash it's vital that the pushrod is on the cam's base circle.
If you manually rotate the the crank till the exh valve is just opening you know the int pushrod is on the base circle; similarly, if the int valve pushrod is just closing you know the exh valve is on the base circle.
BTW, I prefer to twirl the pushrod with thumb & finger while tightening the rocker till I just feel drag, then tighten 1/2 + 1/8 turn more. This sets lash to between 1/2 and 3/4 turn, based on my precision in detecting zero lash.
When setting lash it's vital that the pushrod is on the cam's base circle.
If you manually rotate the the crank till the exh valve is just opening you know the int pushrod is on the base circle; similarly, if the int valve pushrod is just closing you know the exh valve is on the base circle.
BTW, I prefer to twirl the pushrod with thumb & finger while tightening the rocker till I just feel drag, then tighten 1/2 + 1/8 turn more. This sets lash to between 1/2 and 3/4 turn, based on my precision in detecting zero lash.
Last edited by 65Z01; May 2, 2010 at 07:06 AM.
Race Director
Joined: Aug 2000
Posts: 11,470
Likes: 763
why not just follow the procedure in the FSM? i'm assuming your 88 is the same as my 90, so with the engine in the #1 firing position, or TDC, adjust the following:
exhaust -- 1, 3, 4, 8
intake -- 1, 2, 5, 7
now here's what i do for valve adjustment: using a .0015" feeler gauge, between the rocker arm and valve stem, slowly tighten the adjusting nut until the feeler gauge "grabs". at that point, you should be within .001" of zero lash. then adjust the nut 1/2 turn. this method seems a little more exact, or precise than the "rotate the push rod while turning the adjusting nut" method, and should result in a more even adjustment across the board..
now, rotate the crank 1 revolution or 360 degrees, and adjust the following:
exhaust -- 2, 5, 6, 7
intake -- 3, 4, 6, 8
exhaust -- 1, 3, 4, 8
intake -- 1, 2, 5, 7
now here's what i do for valve adjustment: using a .0015" feeler gauge, between the rocker arm and valve stem, slowly tighten the adjusting nut until the feeler gauge "grabs". at that point, you should be within .001" of zero lash. then adjust the nut 1/2 turn. this method seems a little more exact, or precise than the "rotate the push rod while turning the adjusting nut" method, and should result in a more even adjustment across the board..
now, rotate the crank 1 revolution or 360 degrees, and adjust the following:
exhaust -- 2, 5, 6, 7
intake -- 3, 4, 6, 8
Last edited by Joe C; May 2, 2010 at 07:22 AM.
Thread Starter
Racer
Joined: Sep 2001
Posts: 266
Likes: 7
From: Sumner WA
Lots of great advice. Thanks.
I'm obviously new at adjusting valves and I'm always wondering how things work and find different ways to do things. I will likely follow the FSM but that doesn't keep my mind from wondering, what if?
Ron
I'm obviously new at adjusting valves and I'm always wondering how things work and find different ways to do things. I will likely follow the FSM but that doesn't keep my mind from wondering, what if?
Ron
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Drifting
Joined: May 2006
Posts: 1,428
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From: Chewelah Wa
Another observation from someone who has been there, once you tighten the rocker and twist the pushrod so it barely moves, call it good. If you keep rechecking them, they will appear loose, as the lifter bleeds off the pressure. So you keep tightening the rocker. As far as how many turns to go on the adjuster nut, I have heard everything from a quarter turn to a full turn. The TPIS "Insider Hints" book calls for a full turn. I have always done a half turn with no issues.
