What is the purpose of lapping valves?

Lapping valves is a crucial process that ensures a proper fit between the valve and the valve seat. When valves are installed in an engine, a tight seal is necessary for optimal performance; otherwise, compression can escape during combustion, leading to inefficient engine operation. Lapping involves using a fine abrasive compound to grind the surfaces of the valve and valve seat, thereby achieving a precise contact area. This helps in eliminating any imperfections, ensuring that they seat properly against each other to create a seal that prevents air and fuel mixtures from leaking out and exhaust gases from entering the intake system.

This process directly enhances engine efficiency and performance, making it an essential step during engine repairs or rebuilds. The other choices do not accurately represent the primary purpose of lapping valves, leading them away from the main function that directly supports engine performance and efficiency.