Make sure each pushrod is properly seated in the lifter and rocker arm. Also be certain the lifter is on the base circle of the cam before adjustment. With a hydraulic cam, adjust the rocker arm nut until you obtain zero lash with no lifter preload, then turn the nut down one-half to one turn more. Once adjusted, tighten the set screw with an Allen wrench. Detailed instructions are included with the Crane rockers.