Abstract: A valve stem seal assembly includes a rigid cylindrical shell and an annular resilient seal body contained entirely within the shell. Integral to the seal body is a frustoconical sealing element adapted to engage a valve guide of an internal combustion engine. The sealing element converges radially inwardly, and upon installation of the assembly on a valve guide the outer surface of the sealing element bends further radially inwardly to effectively seal the top surface of the guide. The seal body includes a stem sealing aperture, which in one preferred embodiment is designed to engage the valve stem without a spring. In a same or similar embodiment, the shell contains a circumferential array of tangs for retention of the assembly on the guide.

Abstract: A piston comprises a piston pin bore adapted to at least partially contain a piston pin. The bore is finished by a roll burnishing process which substantially simultaneously prestresses, smooths and distorts the bore into a predetermined hourglass configuration.