adjusting valve lash

02 2500 Avalanche · January 10, 2003

I am about to adjust my roller rockers for my big block for my '61 apache. Right now I am just waiting on my push rods from jegs to come in.I just wanted to make sure I know what Im doing when I go to set the valve lash. Correct me if im wrong but you put each cylinder at top dead center and screw the bolt on the rocker till its snug then turn it one complete turn and then turn the set screw 1/4 turn, right? I just wanted to make sure because this is my first engine that I have built ( Im 15 btw) and I want to get it right. Thanks

Alex

02 2500 Avalanche · January 13, 2003

Anyone?

02 2500 Avalanche · January 15, 2003

I just got my comp cams push rods today and I am itching to get them put in so any insight on this would be great. Thanks

Alex

Tjwong · January 15, 2003

Here is a procedure Alex for setting your valves:

Set your engine at TDC (TOP DEAD CENTER) for No. 1 to fire and set the following valves:

Exhaust valves: 1 - 3 - 4 - 8

Intake valves: 1 -2 - 5 - 7

After that is done, rotate the engine clockwise one complete turn (No. 6 at firing position) and adjust the following valves:

Exhaust valves: 2 - 5 - 6 - 7

Intake valves: 3 - 4 - 6 - 8

Now when you adjust these valves what you need to do is to gently tighten down the rocker arm until it "zeros" to the lifter. You can do this by feel, I do it be twisting the push rod back and forth with one hand while I gently tighten down the rocker, the moment I feel the push rod drag a little, that means its at zero lash, once I get to zero I tighten the rocker arm nut exactly 3/4 turn more. Do that for the all valves. Double check if necessary.

If this is your first engine, double check it! Play around with the adjustment so you can get the feel of how the push rod drags a bit when you are twising it back and forth between ur index finger and thumb at the moment the push rod contacts the lifter plunger. If you tighten it down too much thats not good, if its not enough its not good. So get the feel of it and you will get it right. GM recommends one full turn, but for all intents and purposes 3/4 turns is plenty. It gives the plunger a little additional travel if needed. For performance applications I use 1/2 turn after zero lash.

02 2500 Avalanche · January 15, 2003

Thanks Tj. The roller rockers are comp cam pro magnums which have a set screw in the nut. The only thing is that I do not know much I have to set the allen wrench set screw. I think it needs to be turned 1/4 of a turn but Im not sure.

Alex

Tjwong · January 16, 2003

I also use Comp cams pro magnum rockers. After you set your valve lash, you can just tighten by hand the allen screw. I use a combination valve adjustment tool that allows me to hold the rocker arm adjustment nut and tighten the allen screw at the same time. It has a "T" handle allen wrench and I just give it a good twist.

Don't try to twist it so hard as if to break it, using a "T" handle wrench and making it good and tight is all that is necessary. They are made so that both surfaces are parallel ground are self locking.