Abstract: 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.

Abstract: A rotary combustion engine having a completely die cast aluminum housing assembly wherein one of two end housings is rigidly secured and sealed to one open end of an outer barrel housing in which either one rotor housing or two or more rotor housings separated by an intermediate housing are radially confined. The other end housing is secured and sealed to the other open end of the outer housing to clamp the radially confined housing or housings with a predetermined load within the tolerance stack-up of the clamped parts. With this arrangement the outer housing grows with the clamped parts in the axial direction as a result of heat expansion during engine operation to prevent an excessive change in the clamp load while good sealing is maintained.