This what is in my Chevy performance engine book.
Most factory applications recommend that the hyd lifters be adjusted 1 turn down from zero lash,the point where the lifter stops clicking while your adjusting it,
For maximum effect manufacturers usually recommend an adjustment of only one 1/4 turn .
The procedure while engine is running is to loosen each adjusting nut until the lifter starts to click. Then tighten until the clicking stops,once the clicking stops slowly tighten nut 1/4 turn more,if you tighten to fast the lifter will not compensate and the engine will run rough or STALL.
If your adjusting valves in a new engine the procedure is just as simple.
All you have to do is place 2 fingers on the rocker arms just over the pushrods .
Rotate the engine slowly untill you feel them settle as far as possible. The rocker arms should be loose at this time.Continue turning the engine until the pushrods begin to rise.
This means the lifters are off the base circle and they are beginning to move up the clearance ramp.
Work with 1 valve at a time and use the pushrod movement to determine when the lifter is on the base circle of the cam .Make the adjustment by turning down the adjustment nut slowly.While you are tightening the nut ,grasp the pushrod between your fingers and slowly rotate it back and forth .When you have removed all the slack in system you can feel resistance as you twirl the pushrod .This means you are starting to depress the plunger in the lifter. At this point you go ahead and add your 1/4 turn adjustment and move on to the next valve.
By presetting the all the valves in this manner you will be able to start the engine and run in the cam without all the clatter that normally comes with the initial fire up .
The engine will start up and run quietly you can make a back up adjustment after all the parts have become familiar with each other.
My finger now hurts typing this