Perhaps the most significant leap in valve-seat preparation has been the use of a dedicated cutter rather than stones. The Serdi was the first machine of this kind. It uses a hardened-steel cutter ...

we had Chuck Willard of Willard Auto Machine (WAM) in Omaha, Nebraska, further modify its existing 1.96/1.66-inch valve seats to accept 2.11/1.77-inch valves using his Serdi 3.0 valve-seat cutter.

Valve seat inserts produced from this material achieve comparable ... while the softer matrix provides for longer tool life when bevel cutting the seats, for example,” according to Federal-Mogul.