What does insufficient tappet clearance at the inlet valve cause?

Insufficient tappet clearance at the inlet valve leads to late closing of the valve. When the tappet clearance is not adequate, the valve may not seat completely when it is supposed to close, which delays the closing action. This can prevent the cylinder from achieving an optimal combustion cycle, as the inlet valve remains open longer than intended.

This scenario can disrupt the engine's timing and efficiency, as the intake and exhaust cycles may overlap improperly, leading to potential mishaps in cylinder filling and exhaust clearance. Consequently, this can cause other issues such as improper air-fuel mixture and misfires, yet the most immediate impact is the late closing of the inlet valve.