rocker arm adjustment

[Don Izzo]

I couldn't find any information in the service manual for my 1960. They refer me to the 1960 passenger car manual. So I looked in my 68 and my Chiltons manuals. They both say to rotate the engine to the NO. 1 firing position and then adjust the ex. 1,3,4,8 and the intake 1,2,5,7. Then rotate the engine one revolution to the No. 6 Firing position and adjust the ex. 2,5,6,7 and intake 3,4,6,8. The problem is, one manual tells me to add 3/4 of a turn to each valve after removing the lash, the other manual tells me to add 1 full turn, my mechanic said 1/4 turn. Which is it! Can I do these adjustments with all the rocker arms and push rods installed or should I only install the ones I am adjusting? By the way motor has around 500 miles on it, see prior post! After completing this adjustment I intend to run the motor until warm and then loosen the rocker arms one at a time until they clack, then tighten till the clacking sound is gone (zero lash) and then add the required number of turns. Am I just repeating myself with this procedure or is this the common practice? I don't want to bend a push rod! Thanks
Don

[Joe L.]

Re: rocker arm adjustment

Don-----

The procedure described in the manual will work quite well IF you perform it exactly as described. Make sure that you're on right cylinder firing position when you perform the adjustment for each group of valves. If you do it right, there should be no need for a "running adjustment". Keep in mind that MILLIONS of these engines were built by GM and not a single one originally had its valves adjusted "hot and running".

The "official" turns down from zero lash specification as far as GM is concerned is 1 turn. This adjustment centers the plunger in the lifter. I usually use 3/4 turn, though. Some folks use 1/2 turn. I would not use 1/4 turn.

[Clem Z.]

Re: rocker arm adjustment

just install the rocker arms on the valves you are adjustning as this prevents "collapsing" a lifter as you are turning over the engine and you could get a false reading when you adjust that lifter. i do this just to be safe but i prefer to do it with the intake off so i can see the lifter seat move. i would use 1/2 turn to make sure you do not have to do the "hot and running" adjustment

[dick foehringer]

Re: rocker arm adjustment

here is a trick i use. it is very difficult to tell when you are at zero lash. spinning the push rod is a poor way to tell as i have been able to turn them freely after 3/4 over lash. i use a real thin feeler gauge. the thinnest i have. put that between the valve stem and the rocker. as you are tightening it down you will definitely know when you are at zero. i also use 1/2 turn and never had to readjust hot or running.
regards dick

[Roger Legge]

Re: rocker arm adjustment

I also do not spin the pushrods. I move them up and down and after a bit it's easy to tell when you are at zero lash. I go a tad over 1/2 turn and have never had a problem.

Roger

[Michael F.]

Re: rocker arm adjustment

does this procedure outlined in the manual also apply to mechanical )solid) lifters??? thanks.

[Clem Z.]

Re: rocker arm adjustment

it can be used to to rought set the solid lifters BUT i would run the lash one cylinder at a time after this rought setting.