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Final Word on Setting Valve Lash by RotrexFiero
Started on: 08-05-2003 10:45 AM
Replies: 9
Last post by: Capt Fiero on 08-07-2003 02:10 AM
RotrexFiero
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Report this Post08-05-2003 10:45 AM Click Here to See the Profile for RotrexFieroClick Here to visit RotrexFiero's HomePageSend a Private Message to RotrexFieroDirect Link to This Post
Topic says it all...Haynes Manual says 1.5 turns but I believe it was discovered only a half is needed.

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Pyrthian
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Report this Post08-05-2003 10:59 AM Click Here to See the Profile for PyrthianClick Here to Email PyrthianSend a Private Message to PyrthianDirect Link to This Post
I've gone 1/2 turn. wasnt enough. had noisy rockers. being on my 3rd cam, I've done this quite a bit in the last 2 years. last one, I went the full 1-1/2 turns. it seems right. by the depth comp cams recommended for the pre-load, it looked right also. I believe the right lash is at least 1 turn, at most 1-1/2 turns. but this also matters on how you find zero lash point. I did it by the rotating the rods untill I feel the slightest resistance. usually end up passing it up, backing it up, doing again, usually 3 times ebfore i'm confident about my zero spot. I may be thinking I'm at zero before I actually am. either way, it seems right.
theres 2 other things I've heard on this -
one was theres a difference on lash if it's NEW cam & lifters, or just re-doing broke in ones.
two was using a feeler guage to lash down to the specified pre-load by measureing how far the pluger is pushed into the lifter - I like this idea, just dont have the feeler guages...

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RotrexFiero
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Report this Post08-05-2003 12:21 PM Click Here to See the Profile for RotrexFieroClick Here to visit RotrexFiero's HomePageSend a Private Message to RotrexFieroDirect Link to This Post
So what would you suggest for new SS springs, slightly stronger than stock, and a new cam.

I'm thinking 1 turn should do it.

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Smoooooth GT
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Report this Post08-05-2003 12:49 PM Click Here to See the Profile for Smoooooth GTSend a Private Message to Smoooooth GTDirect Link to This Post
What is the correct procedure for doing it(re-doing it) on a used cam from start to finish??

Smooth!!

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Said Hulki, "You had to look at the Fiero not as
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Paul Prince
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Report this Post08-05-2003 01:39 PM Click Here to See the Profile for Paul PrinceClick Here to Email Paul PrinceSend a Private Message to Paul PrinceDirect Link to This Post
 
quote
Originally posted by Smoooooth GT:

What is the correct procedure for doing it(re-doing it) on a used cam from start to finish??

Smooth!!

Manual (Pontiac) says at TDC #1 adjust #1 intake, exhaust then a list of other cylinders (can't remember the numbers) then rotate crank 360* to TDC #4 and adjust the rest. Haynes manual gives same procedure.
OR, go to TDC #1 and adjust #1 intake and exhaust. Rotate to #2 TDC adjust intake/exhaust, move along firing order 1-2-3-4-5-6.
I adjust with lower manifold off so I can see where the pushrod is on the lifter, and I move the pushrod up and down to find 0 lash, rather than the "twist" procedure. The twist procedure can be misleading because the lifter may not have any oil in it so you would adjust "too deep" causing cam wear.
After I adjust all the valves, I find I forgot to put the cylinder head to lower intake gaskets on so I do it again
When you add aftermarket springs, you need to check the installed height and pressure, or you can bend a pushrod, screw up a cam etc. I use 3/4 turn after 0 lash. And, my opinion, the GM lifters and pushrods are the best. I have had a Crane pushrod break the tip off and fortunately found it in the oil pan, not wedged in the crank/rod......Paul

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Smoooooth GT
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Report this Post08-05-2003 05:56 PM Click Here to See the Profile for Smoooooth GTSend a Private Message to Smoooooth GTDirect Link to This Post
Thanks Paul!!
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Dan87GT
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Report this Post08-05-2003 08:10 PM Click Here to See the Profile for Dan87GTClick Here to Email Dan87GTSend a Private Message to Dan87GTDirect Link to This Post
I followed the Haynes manual on my rebuild last summer, 1.5 turns....took me two seeks to figure out why it wouldn't start..never checked the compression...when I did I had zero compression..and I did prime the lifters...I backed them off 3/4 turn and it started right up.....my 2 cents is 3/4 turn..
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Manic Mechanic
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Report this Post08-05-2003 09:43 PM Click Here to See the Profile for Manic MechanicClick Here to Email Manic MechanicSend a Private Message to Manic MechanicDirect Link to This Post
1.5 is too much. You want to use .5 to .75 of a turn.
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jetman
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Report this Post08-07-2003 02:06 AM Click Here to See the Profile for jetmanClick Here to visit jetman's HomePageClick Here to Email jetmanSend a Private Message to jetmanDirect Link to This Post
1.5 is perfect, broke in engine.

This will center the lifter plunger in the middle of the lifter.

Unfortunatly everyone has a different value for zero lash. Zero lash is where there is no vertical play or slop in the push rod. At that point 1.5 turns is perfect.

Now some folks determine zero lash where the push rod meets resistance while turning or twisting it. I have tried 3/4 turn in this case but did not have good results.

Part of the difficulty also results from not being able ot see the lifters themselves due to the lower intake in place.

Paul Prince, you have the easy method of adjusting the lash. Mine came out perfect with that technique. I went the 1.5 turns and engine is very smooth, powerfull and alot quieter than the 3/4 turn I had originaly went with.

Valve lash is a can of worm subjects. There are so many variables, technique, wear, mileage and results. 3/4 turn works for some but 1.5 has worked for me.

Tm

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Capt Fiero
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Report this Post08-07-2003 02:10 AM Click Here to See the Profile for Capt FieroClick Here to visit Capt Fiero's HomePageClick Here to Email Capt FieroSend a Private Message to Capt FieroDirect Link to This Post
I find that 1-1.5 is what worked for me, and I am using Comp Cams Fast Bleed Lifters. Cant remember the exact name, but the Performace shop that I bought them from said there were the best high rpm lifters on the market for flat tappet hyd use. I remeberd just as I clicked submit, they are Comp Cams Pro Magnum Lifters.

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85GT 2.9 4spd MSD Everything, Big Cam, No Cat and Nitrous. Nawzz babeee!!!!
http://www.captfiero.com

[This message has been edited by Capt Fiero (edited 08-07-2003).]

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