Valve Adjustment ... With Engine Running or not ?

Tynan918

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Aug 2, 2021
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I just did an oil change and I have adjusted the valves both with the engine running and while the engine is shut off but I still have light ticking/tapping that gets louder as I accelerate.

At first I thought maybe the engine was low on oil, or I'm not adjusting the valves correctly, but now I'm stumped and can't figure out why I can't get rid of the tapping/ticking.
 

Tynan918

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Aug 2, 2021
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Okay update on the exhaust, I removed the gaskets and went straight manifold to head and have not had an issue yet.. my starter crapped out on me so I haven't really had the chance to take it for a test drive to see how it really goes...
 

Tynan918

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Aug 2, 2021
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I just adjusted my valves with the engine running again and I think it's too tight. I loosened each one at a time until it clacked and turned them in 1 full turn.

Engine sounds good I assume, but my dash vac gauge is rapidly bouncing between 10-13hg @ 1200 RPM. No hesitation when I blip the throttle, but starting seems harder.

Put it in drive and the needle still bounces...

Vacuum gauge never did that until I adjusted these valves.

I'm going to back them off quarter inch at a time until it starts easily, and leave it there.
 

79 USA 1

G-Body Guru
Sep 2, 2011
952
93
Cheektowaga, New York
Here is a YouTube video from Ellison's machine shop.
While some will give their opinion on the best way to set valves this guy's method is one that I've used for many years with hydraulic cams and never had an issue. And yes you can do this adjustment with the intake installed.
Worth the watch and he explains the process which is very easy to understand.
 
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565bbchevy

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Aug 8, 2011
9,210
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I just adjusted my valves with the engine running again and I think it's too tight. I loosened each one at a time until it clacked and turned them in 1 full turn.
I only go 1/2 turn past zero lash and only adjust in 1/4 increments when running and wait for the engine to recover before making another lash adjustment.
 
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stew86MCSS396

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Aug 1, 2022
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I loosened each one at a time until it clacked and turned them in 1 full turn.
Last time I've done it with the engine running and oil splashing everywhere was back in the in 80's. Without employing a modified valve cover or rocker arm oil deflectors, after the engine fire stopped doing it that way. Doing it in that manner, I back it off until it starts clacking, tighten until it stops then I go for another 1/2 turn. One thing you need to understand is what are you trying to set it at? I've seen various responses of .020"-.050" could be dependent on cam manufacture recommendation. So to give it a different perspective, the adjustment nut for the rockers have a 3/8"-24 thread. You can simply take 1" divided by 24=.041666" which is what 1 full turn will get you. Divide it further into fourths, each quarter turn will net you ~.010".

What I don't like is the low vacuum you're experiencing which is on par with what I posted in your id camshaft thread...camshaft with 222*-230* or at least that is what mines idles at. Perhaps other underlying issues seeing how your exhaust bolts were loose, might want to check for vacuum leaks around the intake.
 
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Tynan918

Royal Smart Person
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Aug 2, 2021
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1/2 turn only. On most stock lifters. Once the lifters are set correct, your bouncing needle should smooth out.
That's what I did, I backed out that full turn 1/4 turns at a time until I was able to start the engine. Needle doesn't bounce and just now under load and in gear and cruising without my foot on the pedal, the vacuum reads 18hg...just confirmed that. Throttle response and power have noticably improved, and it growls now when I press the gas...much better, I love it.

Only issue now is that I diesel after shut off in Park, but that may be because of the 87 "non-ethanol" octane fuel I've been using in my high compression engine. Just now learning high compression engines need higher octane fuel. I found 3 gas stations in my area that has REAL non-ethanol 93 octane fuel and another station with REAL 91 octane fuel. Eventually I'm going to fill up at one of the stations starting with 93 and seeing how things change from there.
 
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CopperNick

Royal Smart Person
Supporting Member
Feb 20, 2018
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Canada
Chevrolet or BOP? The first gen SBC's pretty much came from the factory with a tick in the valve train, not loud or the death tick of a dying lifter, just a quiet tick. The consensus of mech's and tuners from decades past was that the tick had been deliberately built in by the factory somehow and that any engine that didn't tick was a clunker. Can't speak to the veracity of that story but did have a cousin (posted about this elsewhere) that did buy himself a new 70 Nova; and it didn't tick. No matter how many times it went to the dealer, still no tick. he got rid of it asap because, along with no tick, it had no go.


Nick
 
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