[Bob In Ct]

No need to use them on intake valves since they are against the head when the fire is burning. When they open a cool intake charge comes by. The exhaust valve, on the other hand, gets a very hot flame all around it 25 times per second at 3,000 RPM. The longer the duration the less time it has to cool against its seat. It's a tough life being an exhaust valve.

Bob