What is the recommended margin after grinding an exhaust valve?

The recommended margin after grinding an exhaust valve is typically between .001 to .003 inches. This narrow margin ensures that the valve can seal effectively against the seat while still allowing for sufficient material for heat dissipation and avoiding excessive wear. A properly maintained margin allows for optimal sealing performance and minimizes the chances of valve seating issues, which can lead to engine performance problems, such as loss of compression or increased emissions.

Maintaining such precision helps in ensuring the longevity of both the valve and its seat in the cylinder head. A margin that's too wide or too narrow can negatively affect the engine's efficiency and durability; thus, the specified range balances operational reliability and performance.