Technician A says that excessive cylinder head or block deck resurfacing on a pushrod engine can change the geometry between the valve stem tip and rocker arm. Technician B says that excessive grinding of the valve face and seat changes the geometry between the valve stem tip and rocker arm.

Who is right?

A. Technician A only
B. Technician B only
C. Both A and B
D. Neither A nor B

Both Technician A and Technician B are correct about the effects of excessive resurfacing or grinding in a pushrod engine, affecting the geometry between the valve stem tip and rocker arm, and impacting valve timing or function. the correct option is A.

Explanation:

The question asks about the effects of excessive resurfacing or grinding within the context of a pushrod engine. Excessive cylinder head or block deck resurfacing can indeed change the geometry between the valve stem tip and the rocker arm, as indicated by Technician A. This is because altering the height or angle of these surfaces can impact how the rocker arm interacts with the valve stem, potentially affecting valve timing and engine compression.

Technician B's statement that excessive grinding of the valve face and seat changes the geometry between the valve stem tip and rocker arm is also true. Grinding reduces the material on these components, which can alter their relation and functionality, impacting how effectively the valves seal and the overall valve timing. Hence, both technicians are correct in their assessments.