On engines equipped with hydraulic tappets, zero lash at maximum tappet plunger rise can be determined by rotating the pushrod with your fingertips while slowly turning the lash adjusting nut.

Where flat tappets get into trouble is oil starvation, improper valve lash adjustment, excessive valvespring pressure, and/or improper break-in. A flat tappet cam’s most critical moment is ...

When adjusting hydraulic flat-tappet or hydraulic-roller lifters for proper preload on a 350 small-block, a 454 big-block, and other displacements and engine makes with non-positive-stop stud ...