Valve Adjustment on stock 283 - Chevelle Tech
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  #1  
Old Sep 9th, 09, 1:00 PM
tm66 tm66 is offline
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Default Valve Adjustment on stock 283

I followed the steps in the manual to tighten the 8 valves with #1 @ tdc, rotate the motor 180 and then tighten the remaining 8. I spun the pushrod till it stopped then added 1 more turn to each nut. The car then ran rough so I backed each nut off 1/4 turn. Everything seemed fine for the last 2 months. I then read a post where you only tighten the nut a 1/4 turn after the pushrod stops spinning with your fingers so I had to tweak. I discovered that I could spin all of the pushrods with my fingers! I followed the procedure again and now the car runs very rough so here are my ?'s:
How do these "loosen" up?
Do you perform this procedure with the motor cold or warm?
How many turns do I add to the nut after I can't spin the pushrod anymore?
Why did the car run better at idle the 1st time when I backed off all 16 nuts by a 1/4 turn?
thanks in advance.
tm
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  #2  
Old Sep 9th, 09, 1:11 PM
rbeckman rbeckman is offline
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Talking Re: Valve Adjustment on stock 283

Quote:
Originally Posted by tm66 View Post
I followed the steps in the manual to tighten the 8 valves with #1 @ tdc, rotate the motor 180 and then tighten the remaining 8. I spun the pushrod till it stopped then added 1 more turn to each nut. The car then ran rough so I backed each nut off 1/4 turn. Everything seemed fine for the last 2 months. I then read a post where you only tighten the nut a 1/4 turn after the pushrod stops spinning with your fingers so I had to tweak. I discovered that I could spin all of the pushrods with my fingers! I followed the procedure again and now the car runs very rough so here are my ?'s:
How do these "loosen" up?
Do you perform this procedure with the motor cold or warm?
How many turns do I add to the nut after I can't spin the pushrod anymore?
Why did the car run better at idle the 1st time when I backed off all 16 nuts by a 1/4 turn?
thanks in advance.
tm
Tom that is the way I do mine except I got to 3/4 turn and I do it cold and seems to run fine. Maybe I'm just lucky and someone will pop on and have a better way or proper way to do it.
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  #3  
Old Sep 9th, 09, 1:42 PM
Rich-L79 Rich-L79 is offline
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Default Re: Valve Adjustment on stock 283

First, get the whole "can't spin the pushrod" concept out of your mind, it is entirely misleading and you are misunderstanding what is meant to be done. You are tightening down the rockers too much thus the valves aren't closing all the way thus it will run poorly. On top of that you can at the very least burn your exhaust valves and at worst bend or break a valve when the piston hits the valve. You may have already done some damage.

The first step is to tighten the rocker until you have the lifter at zero lash, THEN you tighten it 1/4-1/2 turn more. Zero lash means there is no play between the ends of the pushrod and the lifter at one end and the rocker at the other (with the rocker also touching the valve stem). Any additional tightening done after initial zero lash is preload and you don't want any preload beyond the additional 1/4 turn. When you "turned the engine an additional 180 degrees" did you turn the CRANKSHAFT 180 degrees or the camshaft 180 degrees? The cam turns once for each two full turns of the crankshaft remember.

Other things to be sure of: The valve being adjusted MUST be closed all the way (the lifter is on the base circle of the camshaft). There are better more detailed methods for insuring the valve you are working on is on the cam's base circle. With hydraulic lifters it doesn't matter if the engine is cold or hot, but doing them with the engine fully warmed up would be better since the lifters will be pumped up and give a better feel of zero lash.

If this all seems a little confusing, it might be a good idea to find someone with experience doing this to show you how to do it and then watch over you while you do a few yourself to get the hang of it. Don't run the engine any more until you get the valves properly adjusted! You could be doing serious damage to things otherwise.
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  #4  
Old Sep 9th, 09, 2:41 PM
68chevelle533 68chevelle533 is offline
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Default Re: Valve Adjustment on stock 283

One way to set the lash is with the engine running. Back off the nut until you here it tapping, then tighten it until the tapping stops. At this point you have zero lash then you tighten that nut another 1/4-1/2 turn. As you can guess this is messy and you get some oil dripping on the exhaust. I have seen some people put deflectors on the rockers to keep the oil under control or take old valve covers and cut the top off.
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  #5  
Old Sep 9th, 09, 11:00 PM
rkd rkd is offline
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Default Re: Valve Adjustment on stock 283

The spin the pushrod with your fingers method is the one I have the best results with. Did it to my 350 last September and have not touched it since. Seems quiet and runs decently.

However, I have not had much luck with the indexing the cam only a couple times, so I am back to doing it one cylinder at a time, through the firing order. On the 350 I went about 1/2 turn past where the pushrods seemed to resist turning. Note this is with stock flat tappet lifters, rockers and pushrods.

When you check it in the car, unless you are set at tdc on the cylinder you are checking, the pushrods and rockers may seem loose or tight.
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  #6  
Old Sep 9th, 09, 11:15 PM
pdq67 pdq67 is offline
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Default Re: Valve Adjustment on stock 283

The old time Mechanics around my small country town taught me how to spin the p/r's as well as lash a solid lifter cam idling fine!

Right, not running, spin the p/r's, running down until they stop spinning ON THE BASE CIRCLE! And running back off until they click, then BOTH CASES down like a 1/4 to a 1/2 rotation.

pdq67
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  #7  
Old Sep 10th, 09, 10:35 AM
OLDED OLDED is offline
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Default Re: Valve Adjustment on stock 283

Adjust either solids or hydraulics with it idling as slow as it will stay running. It can be messy, but there are the clips you can use to put on each rocker while adjusting to keep the splash to a minimum. An old valve cover with the center cut out to expose the adjustment nuts is good for adjusting hydraulics too. Only do one head at a time, seal up the finished side and go to the other. Solids take a little longer and you need to get the "feel" of the guage pressure to get all the same, but it pays off in the way it runs.
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  #8  
Old Sep 10th, 09, 10:58 AM
engineguy engineguy is offline
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Default Re: Valve Adjustment on stock 283

tm,
I agree with previous posts, the valves (when using a stock cam ONLY) can be set with the timing set at TDC #1 cylinder and TDC #6 cylinder. (However, to get from TDC #1 cylinder to TDC #6 cylinder, you need to turn the engine one full revolution, NOT 180 degrees. Find TDC #1 cylinder, line up the timing mark on the balancer, adjust the valves per your manual, then turn the engine one revolution and line up the timing mark again and adjust the remaining valves). In my opinion, this procedure should only be done if the engine has a stock cam. High performance cams have a significant reduction in overlap, which will affect this procedure. Engines with high performance cams should have the dampener marked at 90 degree internals and the valves should be set at TDC by turning the engine 90 degrees and adjusting the valve lash according to the firing order.

Now once the valves have been adjusted cold (aka bench setting), the engine should be started and brought up to operating temperature - then hydraulic lifters adjusted by backing off until ticking is heard and tightened until the sound goes away. Then the adjusting nut is turned the additional turn (s) or fraction of a turn according to cam specs. Yes, it can be messy, but it is the best way to adjust hydraulic lash/lifter preload. Some cam manufacturers specify cold lash adjustment and some specify hot lash adjustment - go by their recommendations.
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  #9  
Old Sep 11th, 09, 12:57 PM
tm66 tm66 is offline
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Default Re: Valve Adjustment on stock 283

By "rotate the motor 180" I meant that I rotated the motor until the timing mark went one revolution.
Thanks for the posts. I will get er going tonight.
tm
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  #10  
Old Sep 11th, 09, 3:45 PM
kettbo kettbo is offline
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Default Re: Valve Adjustment on stock 283

Tom,
The engine must be rotated one full turn to get 360*

Another common mistake is people push down on the handle/socket while tightening...this puts load on the rocker ball....
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  #11  
Old Sep 11th, 09, 8:00 PM
matt's66 matt's66 is offline
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Default Re: Valve Adjustment on stock 283

I like to do mine running like Mike. Very easy. I have a valve cover with the top cut off for this. I get lazy though and just do it real quick without the cut valve cover and the little oil that spills out just burns off. I have seen high pressure high volume pumps squirt oil right over the fenders and even on the hood!
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  #12  
Old Sep 12th, 09, 1:44 AM
Schurkey Schurkey is offline
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Default Re: Valve Adjustment on stock 283

Quote:
Originally Posted by rkd View Post
The spin the pushrod with your fingers method is the one I have the best results with.
Quote:
Originally Posted by pdq67 View Post
The old time Mechanics around my small country town taught me how to spin the p/r's
The problem with this method is that it works OK when you have a real, live, human mentor standing nearby watching and teaching.

When you type it out on the Internet, there's no compensation for oily vs. clean pushrods, and big, strong fingers and a lot of attitude vs. small fingers and a delicate touch.

You end up with some novice that puts a Vice-Grip hold on the pushrod, and he can spin the pushrod until the lifter bottoms ('cause he's totally focused on spinning that pushrod)--and then he adds his "preload".

So it's REALLY COMMON for newbies to get the preload MUCH too tight.

That's how I bought my boat. Former owner was a Ford man; tightened the living crap out of the rocker nuts. Engine wouldn't run. I backed the nuts off about two turns--and "WALLA!" it fired and ran.

The whole point of "zero lash" is NOT to have as your goal that the pushrod won't spin. The point of "zero lash" is when the free play is gone from the valve train. And you're better off testing that by feeling for up 'n' down play in the pushrod; or by wiggling the rocker when the ratchet and socket is REMOVED from the adjusting nut.
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  #13  
Old Sep 12th, 09, 11:28 AM
tpshea tpshea is offline
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Default Re: Valve Adjustment on stock 283

Quote:
Originally Posted by Schurkey View Post
The problem with this method is that it works OK when you have a real, live, human mentor standing nearby watching and teaching.

When you type it out on the Internet, there's no compensation for oily vs. clean pushrods, and big, strong fingers and a lot of attitude vs. small fingers and a delicate touch.

You end up with some novice that puts a Vice-Grip hold on the pushrod, and he can spin the pushrod until the lifter bottoms ('cause he's totally focused on spinning that pushrod)--and then he adds his "preload".

So it's REALLY COMMON for newbies to get the preload MUCH too tight.

That's how I bought my boat. Former owner was a Ford man; tightened the living crap out of the rocker nuts. Engine wouldn't run. I backed the nuts off about two turns--and "WALLA!" it fired and ran.

The whole point of "zero lash" is NOT to have as your goal that the pushrod won't spin. The point of "zero lash" is when the free play is gone from the valve train. And you're better off testing that by feeling for up 'n' down play in the pushrod; or by wiggling the rocker when the ratchet and socket is REMOVED from the adjusting nut.
This is absolutely the best advice possible. Do not SPIN the pushrods, simply move them up and down while SLOWLY tightening the rocker nut until they just stop having any play. Then go an extra 1/4 to 1/2 turn.
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  #14  
Old Sep 12th, 09, 2:47 PM
Wolfplace Wolfplace is offline
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Default Re: Valve Adjustment on stock 283

Quote:
Originally Posted by Schurkey View Post
The problem with this method is that it works OK when you have a real, live, human mentor standing nearby watching and teaching.

When you type it out on the Internet, there's no compensation for oily vs. clean pushrods, and big, strong fingers and a lot of attitude vs. small fingers and a delicate touch.

You end up with some novice that puts a Vice-Grip hold on the pushrod, and he can spin the pushrod until the lifter bottoms ('cause he's totally focused on spinning that pushrod)--and then he adds his "preload".

So it's REALLY COMMON for newbies to get the preload MUCH too tight.

That's how I bought my boat. Former owner was a Ford man; tightened the living crap out of the rocker nuts. Engine wouldn't run. I backed the nuts off about two turns--and "WALLA!" it fired and ran.

The whole point of "zero lash" is NOT to have as your goal that the pushrod won't spin. The point of "zero lash" is when the free play is gone from the valve train. And you're better off testing that by feeling for up 'n' down play in the pushrod; or by wiggling the rocker when the ratchet and socket is REMOVED from the adjusting nut.
Excellent advice

As far as adjusting them running,,
Haven't for probably 30+ years when I learned how to do them correctly without applying a rust preventative to the outside of an engine,,,
Just don't see any reason to make a mess & burn my fingers & it is way to easy to do it correctly with the engine off

Ever been to the drags?
Ever been to a dyno room?
Probably 99% of the performance shops in the country?
How many folks do you see adjusting the valves with the engine running,,,,
But to each his own,,,,
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  #15  
Old Sep 12th, 09, 8:12 PM
Rich-L79 Rich-L79 is offline
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Default Re: Valve Adjustment on stock 283

Quote:
Originally Posted by Schurkey View Post
The problem with this method is that it works OK when you have a real, live, human mentor standing nearby watching and teaching.

When you type it out on the Internet, there's no compensation for oily vs. clean pushrods, and big, strong fingers and a lot of attitude vs. small fingers and a delicate touch.

You end up with some novice that puts a Vice-Grip hold on the pushrod, and he can spin the pushrod until the lifter bottoms ('cause he's totally focused on spinning that pushrod)--and then he adds his "preload".

So it's REALLY COMMON for newbies to get the preload MUCH too tight.

That's how I bought my boat. Former owner was a Ford man; tightened the living crap out of the rocker nuts. Engine wouldn't run. I backed the nuts off about two turns--and "WALLA!" it fired and ran.

The whole point of "zero lash" is NOT to have as your goal that the pushrod won't spin. The point of "zero lash" is when the free play is gone from the valve train. And you're better off testing that by feeling for up 'n' down play in the pushrod; or by wiggling the rocker when the ratchet and socket is REMOVED from the adjusting nut.
That is EXACTLY what I was trying say. I'm glad you posted with more eloquence than I did!
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