Abstract: A push rod and method of making same is provided which includes the step of cold extruding an irregularly shaped internal bore into the inner wall of an elongated hollow tube, thereby increasing the internal surface area and internal volume over conventional straight-walled tubes. In the preferred embodiment, the internal bore is defined by a cross-section of an equal number of alternately connected convex and concave portions which result in a varying wall thickness about the perimeter of the push rod. The thick wall regions are designed to be located diametrically opposite the thin wall regions.

Abstract: A one-piece push rod and method of making same is provided which includes the step of swaging at least one end of a hollow tube to define a seat portion having an extended spherical surface for inhibiting interference with a rocker arm socket. Preferably, the tube is characterized by a thicker middle portion which tapers down to the ends of reduced diameter. The spherical seat portion having an arc of revolution extending through an angle of at least approximately 210.degree. and having a constant wall thickness is formed by first machining a taper on the tips, then cold forming the tapered tips with a punch and finally swaging the extended spherical surface.