Valve lash adjustment

[65-72 chevytoys]

Anyone have a proceedure and sequence for adjusting the valve lash in a 72 sbc? I have a noisy rocker or lifter. I have used search, but could not find what I am looking for.

[wedgemon]

This should help...

Valve Lash
ADJUSTMENT

Fig. 1: Intake (I) and Exhaust (E) valve arrangement — except V6 engines



Remove the rocker covers and gaskets.
Adjust the valves on V8 and V6 engines as follows:

Crank the engine until the mark on the damper aligns with the TDC or 0 degree mark on the timing tab and the engine is in the No. 1 firing position. This can be determined by placing the fingers on the No. 1 cylinder valves as the marks align. If the valves do not move, it is in the No. 1 firing position. If the valves move, it is in the No. 6 firing position (no. 4 on V6) and the crankcase should be rotated one more revolution to the No. 1 firing position.
With the engine in the No. 1 firing position, the following valves can be adjusted:
V8: Exhaust 1, 3, 4, 8
V8: Intake 1, 2, 5, 7
V6: Exhaust 1, 5, 6
V6: Intake 1, 2, 3
Back out the adjusting nut until lash is felt at the pushrod, then turn the adjusting nut in until all lash is removed. This can be determined by checking pushrod end–play while turning the adjusting nut. When all play has been removed, turn the adjusting nut in:
1⁄2 –1 1⁄4 additional turn (flat lifter)
3⁄4 –1 1⁄4 additional turn (roller lifter V8)
Crank the engine 1 full revolution until the marks are again in alignment. This is the No. 6 firing position. The following valves can now be adjusted:
V8: Exhaust 2, 5, 6, 7
V8: Intake 3, 4, 6, 8
V6: Exhaust 2, 3, 4
V6: Intake 4, 5, 6
Reinstall the rocker arm covers using new gaskets or sealer.
If applicable, install the distributor cap and wire assembly.
Adjust the idle speed.

- Dave

[65-72 chevytoys]

Thanks that is what I was looking for.

[RyanG]

I recently cut up and old valve cover I had and put it on the head. Started the truck and tightened the rocker arms until the ticking stopped. Fastest way for me. Maybe the other way works better for you. Just another option for ya.

[ulakovic22]

EVOIC is not exactly the fastest but you will never get it wrong.

[Marv D]

Originally Posted by ulakovic22

EVOIC is not exactly the fastest but you will never get it wrong.

...and you will be dead accurate using the Intake valve closing / exhaust valve opening method. If you flip a motor over and look at the lifter sitting on the lobe of a big duration cam, you'll see the IC/EO methos is deadly accurate. You'll find many (if not most) use ONLY this method on race motors with solid cams where having lash set dead accurate is a MUST, or damage results.

which.,.,.., just a little pet peeve of mine. With hydraulic lifters your setting PRELOAD in the lifter, and you can use most any method,. The intent and design of the hydraulic lifter is to take up any slack and preload the hydraulics so there is no 'lash'. You only have LASH with a solid lifter. Sorry, tried to bite my tongue but just couldn't do it.

[shortbed70]

Speedwaymotors also has one that you can use it takes a little while to do but works you adjust two valves at a time and when I did mine no more problems.

[65-72 chevytoys]

Guys thanks for the help. I adjusted the valves as described above zero lash and then 1/2 turn. When I put the covers back on and started the truck, I still have valve train chattering. Did it not tighten enough or should I keep going in 1/4 turn increments until I get to 1 and 1/4 turns tight to see if that stops the rattle?

[70rs/ss]

NO! 1/2- 3/4 past contact (not running) or past the click going away while running, anything more than that and you can cause the lobe to go flat, bend a pushrod, or worse have a valve hit the piston! If still noisy, and aftermarket cam can cause a clatter from the valve slamming shut. Try to isolate the noise with a stethescope or a big screwdriver to your ear, once narrowed down then you can fix it.

[Jtrux]

Lifter bad maybe, how many miles on them??

[70rs/ss]

flat cam lobe too, but we need to know if it is rock stock or aftermarket cam, and is it adjusted correctly, is it one lifter or general clatter every where, etc, etc??

[ulakovic22]

Originally Posted by 65-72 chevytoys

Guys thanks for the help. I adjusted the valves as described above zero lash and then 1/2 turn. When I put the covers back on and started the truck, I still have valve train chattering. Did it not tighten enough or should I keep going in 1/4 turn increments until I get to 1 and 1/4 turns tight to see if that stops the rattle?

The hardest part of setting lash is getting to TDC, that's why many people do it the EVOIC method to ensure that they are on the base circle of the cam. I'm not too familiar with flat tappets, but most stock rollers spec out at 1 turn +/- 1/4 turn. Get a friend and run the valves again and if it's still there like 70rs/ss suggested I would try to pinpoint where the noise is coming from and go from there.

[65-72 chevytoys]

It is a stock 307 and has the original cam as far as I know.

[70rs/ss]

Probably a flat cam lobe then, if it has a zillion miles, is it bad clicking, or just a tick?? Does it run OK otherwise, no popping or backfiring?? If not then drive it as is, becasue a new lifter could kill the can lobe too??

[65-72 chevytoys]

I cannot confirm the miles from the PO but if the odometer is correct 130k. It is pretty loud, but otherwise no popping or backfiring. I adjusted the valves a second time and instead of 1/2 turn, this time I went 3/4 turn past 0 lash. I thought I had it because the tick went away so I think the extra 1/4 helped. But today after driving for a while it came back. Can the nuts on the rocker studs come loose in just a few miles and should I adjust it again with some thread lock to help the nuts stay in place? Thanks for the help.

[hotrod 80]

Yes , the rocker nuts can get hair line cracks and back off . I bought a Pontiac Lemans for cheap and replaced the rocker nuts . Ran like a champ .

[65-72 chevytoys]

When the timing tab is at 0 deg. Is the TDC when the valves move or do not move? And which one do I adjust the nuts on? I did as described above when the valves on #1 cylinder do not move, but when I turn it over to do the rest. The valves are loose again indicating I might be tightning #1 while on the lobe of the cam?



So tighten when #1 valves move or stay closed?

[kissingbug1978]

TDC(top dead center) is the "top" of piston travel on the compression stroke. http://www.chevyhiperformance.com/te...dex.htmlession meaning valves closed.

[65-72 chevytoys]

That is what I read above in wedgemon's post and the way I did the proceedure. So why are the valves that I just tightened loose again when I rotate the engine? This is why I am confused because I thought TDC was the compressionn stroke inbetween the Intake valve closing and the exhaust valve opening. Therefore 0 deg. TDC the valves should be moving correct???

[kissingbug1978]

Well according to wedgemons post you adjust both valves for #1 when the valves are closed at the same time. In the article I posted it states that you should be adjusting the intake valve when the exhaust valve is about 1/2 way open.

[70rs/ss]

When you say loose, how loose, the lifters bleed off pressure so even though you just tightened them down to 1/2-3/4 of a turn the pushrod will still spin and if you push on the rocker tip it move, but once oil is pushed into the lifter when the engine starts the lifter "pumps up" with oil, so do not sweat it. I just do one cylinder at a time, the intake opens, then closes, then the exhaust opens, then closes adjust that cylinder. Go to the next, it takes a little more time, but all valves are adjusted correctly and you don't get confused! Pull the plugs as it is easier to turn the engine over that way. Buy new rocker arm nuts at checker, Autozone, etc before you bother to readjust the lifters, since they are crimped from the factory and loose the crimp which will allow them to backoff very easily. Once you have new nuts on there, adjust them one cylinder at a time and then change your oil to a 10W40 or 20w50 and it should be quiet. Our older motors (flat tappet cams, etc) do not care for the 10w30 or thinner oils, especially one with over 100k miles, it needs a little thicker oil.

[65-72 chevytoys]

Thanks I will adjust them again using the open and closing method this time. I already have new nuts because I already suspected the old ones backing off. Do I need to crimp the new nuts or just tighten?

[70rs/ss]

The new nuts should be crimped if they are rocker arm nuts. They will be tight going down, which is what prevents them from backing off.

[65-72 chevytoys]

Well I did it both ways and I could not keep the rockers from coming loose. I kept rotating the engine and the valve that I just adjusted kept coming loose even with new nuts. I think I have over tightened them because it wont start now.
I just hope it is not a ground cam.

[Bustacrab]

quick question with this, once adjusted, will you be able to spin the pushrods at all? or should the be snug?