Which angle is correct for refacing a valve?

The correct angle for refacing a valve is grinding to factory specifications. This ensures that the valve fits properly within the engine's cylinder head and creates a tight seal when closed. Factory specifications are provided by the manufacturer and take into account the precise requirements for each specific engine, including the angle of the valve face and the condition of the valve seat.

Grinding to the correct factory specification also helps maintain proper engine performance, efficiency, and longevity. Deviating from these specifications can result in misalignment, poor sealing, and potential engine damage. Thus, adhering to factory specifications is crucial for successful valve refacing.