I have a stock 87gt. According to the 87 factory manual it says to turn pushrods with your hand while tightening rocker bolt ,when you can't turn the pushrods anymore then tighten another one and a half turns. Of course this is after setting the # 1 to TDC and so on. My question is is this correct?
What do you mean, "According to the 87 factory manual" ?
Let me guess, you have the Haynes book?
I hope so, because what they mean is one-half turn, NOT one and a half.
The fellows at the machine shop told me 1/2 and no more than 3/4 depending. This is also what two other engine builders indicated, but leaning more towards 1/2. Tighten them too much and it will result in premature wear on the cam and lifters - too loose noise and it hurts valve lift.
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From the Comp Cams roller tip rocker installation instructions:
"When you feel resistance on the pushrod, you are at zero lash. Tighten the adjusting nut one-half turn more."
[This message has been edited by mindscape (edited 02-21-2002).]
on the 2.5l the valve lash is adjusted by turning the pushrod with your finger tips while tightening the rocker arm nut.
when the rocker arms just touch the pushrods, and you can feel it with a very slight drag. That is when you turn the rocker arm nut an additional 1/2-1 turn.
Your not trying to tighten the nut down until the pushrods cant turn, just until theres a slight drag. Because the engine needs the pushrods to spin.
my "how to rebuild your gm v-6" book, suggests just like how i stated above, but says to tighten it down to 1 1/2 turns. Usually only two threads are showing past the rocker arms.
[This message has been edited by fierospeeder (edited 02-21-2002).]
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04:10 AM
tesmith66 Member
Posts: 7355 From: Jerseyville, IL Registered: Sep 2001
Make sure the lifter is on the cam base circle when you do this. With a stock or stock replacement cam, I go about 3/4 turn. With a higher lift aftermarket cam, I go 1/2 turn. Turn it too much and the valve will be held open all the time causing compression loss.
------------------ Timothy E. Smith 1986 SE V6 1984 Coupe 1996 Ford Probe GT 1999 Chevrolet Silverado Z71 1975 Chevrolet ElCamino SS
Originally posted by mindscape: What do you mean, "According to the 87 factory manual" ?
Let me guess, you have the Haynes book?
I hope so, because what they mean is one-half turn, NOT one and a half.
The fellows at the machine shop told me 1/2 and no more than 3/4 depending. This is also what two other engine builders indicated, but leaning more towards 1/2. Tighten them too much and it will result in premature wear on the cam and lifters - too loose noise and it hurts valve lift.
I have the 1987 PONTIAC FIERO SERVICE MANUAL sold by GM. It says on page 6A2-14 "With the engine in the #1 firing position, the following valves may be adjusted. Exhaust -- 1, 2, 3 Intake -- 1, 5, 6
- Back out adjusting nut until lash is felt, at the push rod, then turn in adjusting nut until all lash is removed. (This can be determined by rotating push rod while turning adjusting nut). When lash has been removed, turn adjusting nut in 1 1/2 additional turns (to center lifter plunger)." By the way the chilton's manual says the same .
I went back and read old threads about valve lash ajustments. I think I now understand what I did wrong.DON'T LAUGH :I followed the manuals advice 'but when I went back and checked the spin-ability of the push rods they were spining again so I retightened them acording to the manual again. Bottom line is the lifters must be bottomed out now. I haven't run the engine yet , the valve covers and the intermediate intake are still off.Do I need to(or should I say :can I) turn over engine to get oil back in the hydrolic lifters or do i have to take off the lower manifold(just put a new gasket on) , so I can adjust valve-lash now that I finally understand? Thanks for the info and any future info would be appreciated. Lindsay
[This message has been edited by fee-air-oh (edited 02-21-2002).]
theres two ways of doing it. With the car off and while the car is running.
What your doing now is all you have to do.
When your doing it with the car running, you have to adjust the lash on the pushrod. Turn off the car, and allow the lifters to bleed, then you can turn the rocker arm nut 1/2 turn.
What we have here is a technical writers nightmare. Is the semantic meaning of 1 1/2 mean one-and-one-half turn, or does it mean one-half turn? In my case I went with the professional builders recommendation.
What to do?
Back them all out and start the procedure from the beginning. The gist of the procedure is to remove all free-play between the lifter, pushtube, and rocker arm, AND center the lifter plunger. When spinning the pushtube, zero lash is the point where you feel drag - additionally there is no free play in the push tube up/down. I make this adjustment slowly. When you hit the zero lash point you will still be able to spin the pushtube, but there will be noticeable drag - maybe not as much as you would think. Then go the additional one-half turn to center the lifter plunger.
If you a leary on doing this, then talk to several people who build engines and get their individual perspectives. Some of the nicer fellows at a machine shop, or a fellow who builds engines, may even let you hang-out and watch an engine assembly. All I can say is there is much to be learned vicariously from the professionals.
Originally posted by mindscape: What we have here is a technical writers nightmare. Is the semantic meaning of 1 1/2 mean one-and-one-half turn, or does it mean one-half turn? In my case I went with the professional builders recommendation.
What to do?
Back them all out and start the procedure from the beginning. The gist of the procedure is to remove all free-play between the lifter, pushtube, and rocker arm, AND center the lifter plunger. When spinning the pushtube, zero lash is the point where you feel drag - additionally there is no free play in the push tube up/down. I make this adjustment slowly. When you hit the zero lash point you will still be able to spin the pushtube, but there will be noticeable drag - maybe not as much as you would think. Then go the additional one-half turn to center the lifter plunger.
If you a leary on doing this, then talk to several people who build engines and get their individual perspectives. Some of the nicer fellows at a machine shop, or a fellow who builds engines, may even let you hang-out and watch an engine assembly. All I can say is there is much to be learned vicariously from the professionals.
Cheers!
Thank you for your info. DO I have to have oil in the hydrolic lifters to do this? I am worried because I may have sqeezed the oil out of them.But it would be great if I could just go through the procedure again(not over tightening them of course. Still wondering.: Lindsay
Originally posted by mindscape: "DO I have to have oil in the hydrolic lifters to do this? I am worried because I may have sqeezed the oil out of them."
No, because the lifters are spring loaded you can do this without pumping them up.
Thanks you were right an I'm back in business Also thanks to all who ventured an opinion. Lindsay
