[bobcowan]

Comp Cams has an excellent article on their web site on exactly how to do this job.

Finding zero lash is actually pretty easy. Turn the nut with your hand. You'll feel it when it hits resistance. That's zero lash.

Don't use the "push rod spin for drag" any more. Once they're adjusted correctly, I can still spin the push rods by hand.

How much to turn past the zero lash depends on the set up. There's the variables mentioned above. AND, some lifter makers recommend more or less lifter pre-load. Ford recommends 2/3 turn for their SB lifters. I have a specially modified set, and only 1/3 is recommended for them. So check with whoever made the lifters.

You could always put a dial indicater on the tip and measure the pre-load exactly.