Abstract: An inverted cup follower is fitted in a bore of the cylinder head of an internal combustion engine in line with the upright stem of an intake or exhaust valve. Such follower has a threaded central bore receiving a complementally threaded plug. The plug has a rectangular socket receiving the rectangular tongue of a cap member which is turnable so as to advance the plug toward or away from the valve stem and thereby adjust the valve clearance. To maintain a desired adjustment, a spring-loaded locking pin normally is received in any one of several closely spaced peripheral notches of the cap member so as to prevent rotation of the cap member relative to the inverted cup follower. The pin can be moved to an unlocked position to permit rotating adjustment of the cap member and the central plug.

Abstract: In an overhead cam internal combustion engine, an adjustable thickness shim assembly is interposed between the end of a valve stem and the underside of a conventional inverted cup follower engaged by the cam shaft. A body component of the shim assembly forms a ramp for a tapered wedge component which is slidable along the ramp to adjust the effective thickness of the shim. The body component has an inclined threaded bore adjacent to the wedge component receiving a screw which when turned advances along the ramp to butt against the wedge component. The body component is formed of a material having a higher coefficient of thermal expansion than the screw such that when the engine is cold the screw is pinched in its bore and will not turn. When the engine is warmed to normal operating temperature, the body component expands to a greater degree than the screw and the screw is free to turn.