What should be done after lapping the valves?

After lapping the valves, thoroughly cleaning the cylinder head in soap and hot water to remove all traces of grinding compound is essential for several reasons. The grinding compound used during the lapping process can be abrasive and leave residues that may interfere with the sealing surfaces of the valves and seats. If this compound remains, it can lead to poor sealing, increased wear, and ultimately affect engine performance.

Cleaning the cylinder head not only removes the grinding compound but also prepares the surface for the installation of the valves. It ensures that no contaminants can compromise the mating surfaces, thereby promoting optimal sealing and engine efficiency. Using soap and hot water helps to effectively break down and remove any stubborn residues.

In contrast, leaving the cylinder head as is could lead to these persistent issues. Installing the valves without cleaning would be irresponsible, as it risks damaging the new seating and could result in failures. Air drying without washing means the harmful grinding compound remains, perpetuating the same risks associated with inadequate cleaning. Therefore, option B is the critical step that must be taken to ensure the reliability and performance of the engine after valve lapping.