15 Check with your camshaft manufacturer for the suggested valve lash if you're running a solid cam. Normally, lash for a race motor is around 0.018-inch on the intake valves and 0.020 on the exhausts. You can check this with a feeler gauge. Use the lock nut to add or remove lash. If you're running a hydraulic cam, the usual practice is to tighten the lock nut until all the lash is removed (spin the pushrod while tightening the nut until you begin to feel some drag on the pushrod), and then tighten it an additional half-turn. If this is final assembly, a little extreme pressure lube between the end of the pushrod and the lifter's pushrod cup will help protect this area during initial start up.