[Wade Chamberlain]

typically it should be about 1/2-3/4 turn beyond zero lash. If you have stud mounted rockers, lock 'em down and you're set.

If you have pedestal mount, they should torque up within 1/2-1 turns beyond zero lash. If they don't torque up, you need longer pushrods. If they torque up too soon, you'll need to shim under the pedestal.

EDIT - I should have mentioned that the adjusting should be done while that particular lifter is on the base circle of the cam (i.e. when the cylinder is at TDC on compression)