Valve lash adjustment
Thread Starter
Safety Car
Joined: Aug 2009
Posts: 3,750
Likes: 275
From: Melbourne, Victoria, Australia
Valve lash adjustment
Hi an odd one here with my freshly built 383, I did the usual adjust the valve lash turn till the pushrod resists being turned and tighten one extra turn, now i have done this many times before but encountered a problem.
The engine ran rough... very rough which turned out the valve lash on
cylinders 2 and 4. there was no compression, i double checked the valve last adjust it was correct but i could only get compression with only a quarter turn on these 2????? is it a problem with the lifters?
The lifters and cam are brand new and all the others are fine?
Well i have put some miles on her now and she runs great
I will check the adjustment and re torque the head bolts on her first oil change after i put another 400 Km on the engine. Has anyone had this happen to them ?????
Maybe the lifters are starting to settle as i can hear the tappet noise is slightly louder. Any ideas guys ????
The engine ran rough... very rough which turned out the valve lash on
cylinders 2 and 4. there was no compression, i double checked the valve last adjust it was correct but i could only get compression with only a quarter turn on these 2????? is it a problem with the lifters?
The lifters and cam are brand new and all the others are fine?
Well i have put some miles on her now and she runs great
I will check the adjustment and re torque the head bolts on her first oil change after i put another 400 Km on the engine. Has anyone had this happen to them ?????
Maybe the lifters are starting to settle as i can hear the tappet noise is slightly louder. Any ideas guys ????
Le Mans Master
Joined: Aug 2010
Posts: 9,272
Likes: 17
you dont say which maker of the lifters , and it does make a difference, but engine off and cold, I would adjust all of them to 1/4 and see how it runs. if you get lifter noise, adjust them running. The maker of my cam and lifters spec's 1/4 turn, which I thought was a bit shallow, but it works perfect.
Thread Starter
Safety Car
Joined: Aug 2009
Posts: 3,750
Likes: 275
From: Melbourne, Victoria, Australia
Thanks 
They are about 1/4 to 1/2 a turn, there was no info sheet that came with the engine. The 85 vette shop manual notes 1 turn, but hey that is standard. I will re-do all the valve adjustments after the weekend and will use 1/4 turn. Was strange that 2 cylinders only were affected, i did the adjustments with the engine on an engine stand and was precise.
Just filled her up with premium 98 octane fuel and wow she flies
Thanks for your help
They are about 1/4 to 1/2 a turn, there was no info sheet that came with the engine. The 85 vette shop manual notes 1 turn, but hey that is standard. I will re-do all the valve adjustments after the weekend and will use 1/4 turn. Was strange that 2 cylinders only were affected, i did the adjustments with the engine on an engine stand and was precise.
Just filled her up with premium 98 octane fuel and wow she flies
Thanks for your help
Race Director
Joined: Apr 2002
Posts: 10,036
Likes: 346
From: Anaheim CA
I always adjust mine hot and running. Then you really know they're right.
One trick I figured out a few years ago: check how much stud is showing above the adjusting nut. I found mine were very close to 0.200" on all of them. If one or more is way off then that may be a clue.
One trick I figured out a few years ago: check how much stud is showing above the adjusting nut. I found mine were very close to 0.200" on all of them. If one or more is way off then that may be a clue.
Thread Starter
Safety Car
Joined: Aug 2009
Posts: 3,750
Likes: 275
From: Melbourne, Victoria, Australia
Thanks Cliff
That is what i did the other day to the right bank, and yes i did check the adjust nut heights on the studs they are all very close to each other in height. Am thinking of getting a used rocker cover, drilling holes big enough to get a socket on each stud, i just hate the oil splashing on my hot headers
I am so surprised at how quiet and easy revving this 383 engine is
That is what i did the other day to the right bank, and yes i did check the adjust nut heights on the studs they are all very close to each other in height. Am thinking of getting a used rocker cover, drilling holes big enough to get a socket on each stud, i just hate the oil splashing on my hot headers
I am so surprised at how quiet and easy revving this 383 engine is
Last edited by gerardvg; Aug 25, 2012 at 04:10 AM.
Race Director
Joined: Aug 2000
Posts: 11,470
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the problem is getting the "turn the push rod thing" even across the board. try this - use a .0015 feeler gauge. carefully, and slowly, tighten the adjusting nut until the feeler gauge grabs. at that point, you are within .001" from zero lash. adjust the nut another 1/2 turn. i've been using this method for several years now - no issues. i feel you get a more even adjustment across all valves and all cylinders.
Last edited by Joe C; Aug 25, 2012 at 04:26 AM.
Le Mans Master
Joined: Sep 2006
Posts: 6,050
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From: Phoenix AZ
2021 C4 of the Year - Modified Finalist
For the oil splashing thing, I got some aluminum sheet about .040 thick, and cut the edge to fit close to my head. then laid a rag across it, and no oil on the headers. Just make sure the rag doesn't touch the exhaust.
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Race Director
Joined: Apr 2003
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From: moraga ca
As mentioned before, the brand of lifter makes a difference. Some of the Comp Cams hydraulic rollers require 0 lash or 1/8 of a turn. The Crane ones that I am using require 2/3 of a turn from 0 to get the plunger in the right position in the lifter. Stock lifters are different too.
Safety Car
Joined: Nov 2009
Posts: 3,973
Likes: 341
From: Adelaide South Australia
Hi Gerard, I had the same issue with my 85 when I put a new hydraulic cam and lifters in, because they are hydraulic and new the amount of oil in the lifter increases after run in and the lash that you set cold and new will now alter on some of the lifters,
so after the 20 minute run in on the new cam and lifters (or lifters that have been out of the engine and drained of oil) it pays to re-set the whole lot again
so after the 20 minute run in on the new cam and lifters (or lifters that have been out of the engine and drained of oil) it pays to re-set the whole lot again