LAPPING THE VALVES
When valve faces and seats have been re-faced and re-cut, or if they are determined to be in good condition, the valves must the "lapped in" to ensure efficient sealing when the valve closes against the seat.
- Invert the cylinder head so that the combustion chambers are facing up.
- Lightly lubricate the valve stems with clean oil, and coat the valve seats with valve grinding compound. Install the valves in the head as numbered.
- Attach the suction cup of a valve lapping tool to a valve head. You'll probably have to moisten the cup to securely attach the tool to the valve.
- Rotate the tool between the palms, changing position and lifting the tool often to prevent grooving. Lap the valve until a smooth, polished seat is evident (you may have to add a bit more compound after some lapping is done).
- Remove the valve and tool, and remove ALL traces of grinding compound with solvent-soaked rag, or rinse the head with solvent.