Engine with valve seat inserts and method of retaining

摘要

A valve seat insert of relatively hard (e.g. ferrous) material is positively retained in a recess around a gas flow port in the relatively softer (e.g. aluminum) wall of an engine combustion chamber by deforming a portion of the wall material against a chamfer provided at the outer edge of the insert. The deformation may be accomplished by machining or rolling the proud edge of the wall recess against the chamfer. The port flow may be improved by machining a shallow dished area about the valve seat at the end of the insert and the adjacent wall and the machining step may be used to also deform the wall material against the chamfer or it may follow the deforming step.