Hi guys. I've read alot of posts on adjusting the hyd. valves. I'm all for the one full turn, idling method. It can be a little messy, but I usually have good luck that way. I have a concern however. I built a 350 and put it in my 86 Camaro. I set the valves at 3/4 turn. The car ran like crap. I couldn't set the idle mixture, I had popping out the exhaust. Then I set them at 1/8 turn. Seems to run fine. Was able to set my idle mixture, and the popping is gone. It's a comp cam with 470 lift, adv. 270 duration and 110 separation. Comp cam even recommends 3/4 turn. Heads are brand new aluminum 2.02/1.60 and I'm using steel roller tip rockers. Could there be another problem that I am not seeing, or should I just leave it at 1/8 turn?

 

If this was with stock or weak valvesprings, then that's what the problem was. More preload digs into the spring inside the lifter, which in turn reduces the seat pressure the valvespring can provide, and sometimes not allow the valves to seat correctly.

For a stock application a lot of preload is ok with a stock cam. For a performance application where you're pushing the RPM, it's better to run very little preload on a hydraulic lifter.

I would go back and re-do your preload, first by visually verifying that your lifter plungers are starting out all the way at the top against the clips. Then do the adjustment the correct way, - not with the engine running.

 

Here are step by step instructions:

1. Remove the valve cover.
2. Identify the number one cylinder. Turn the engine over until you see the number one cylinder exhaust valve rocker arm JUST START to move from the closed position to open. You may need to turn the motor over a couple of times to reach this point, but do not turn any further.
3. Locate the intake valve.
4. Loosen the rocker arm adjustment nut until you feel some obvious lash or clearance in the adjustment.
5. Using the thumb and index finger of one hand, grasp the intake push rod below the rocker arm, and rotate it back and forth (clock-wise and counter clock-wise successively to be sure there is no remaining pressure on the push rod from the rocker arm as you loosen the rocker arm adjusting nut.
6. Using the other hand, while continuously performing step 5, with a 5/8 socket and ratchet, tighten the rocker arm adjustment nut slowly until you feel a resistance of motion on the push rod.
7. This will be the zero lash adjustment point. For hydraulic lifters, tighten the rocker arm adjustment nut 3/4 of a turn. For solid lifters, back off the rocker arm adjustment nut until your feeler gauge just fits under the contact point between the valve stem and the rocker arm. Fine tune the adjustment by checking it with a feeler gauge just slightly thicker than the preferred clearance to be sure the clearance is not greater than it should be. If the larger feeler gauge will fit, it needs to be re-adjusted. A lash tolerance of 1-2 thousandths of an inch in the valve adjustment for solid lifters would be acceptable since it may be difficult for someone who is in-experienced to be more precise than that.
8. Turn the engine over until the intake valve opens and then is almost closed.
9. On the exhaust valve, repeat steps 5 through 8 for the exhaust valve adjustment.
10. Repeat this procedure for each cylinder. Be sure to do each cylinder sequentially, either following the firing order, following the cylinders numerically, or in the case of a V8 doing one side of the engine at a time. I prefer to do one side of the engine at a time