A tappet clearance setting apparatus includes a screwdriver, a pneumatic portion, and a controller. The screwdriver engages the tappet screw and the pneumatic portion provides a monitored and air flow through an engine cylinder. The controller directs the screwdriver to tighten the tappet until the air flow through the cylinder is indicative of a valve opening. The controller then directs the screwdriver to reverse directions until the sensed air flow indicates that the valve has closed, which further indicates that the tappet screw is in a reference position. From the reference position, the controller directs the screwdriver to loosen the tappet a predetermined amount to establish the desired tappet clearance.