Abstract: A low mass two-step valve lifter has concentric inner and outer cylindrical cam followers engagable by radially disposed axially aligned lock pins in the outer high lift follower. Both inner and outer followers have cylindrically crowned cam engaging surfaces for high lift capability and low load eccentricity. The lock pins are positioned on the lifter thrust axis normal to the direction of the engine camshaft axis and the skirt has upward seal extensions and downward extending skirt portions adjacent the lock pin openings to maintain seal area. Other skirt portions are cut away to reduce weight. Vent holes in the lock pins discharge collected oil that might interfere with fast pin engagement. A separate passage is provided to feed oil to a hydraulic lash adjuster disposed in the inner follower cylinder. A single guide pin aligns the dual followers with the external bore oil ports and the camshaft cams. Additional features are also disclosed.

Abstract: Compact valve lifters are disclosed for overhead camshaft engines with direct acting valve gear and for engines with indirect acting valve actuation such as push rod actuated overhead valves. Two step variable lift and non-variable lift valve lifters are included as are roller and non-roller follower types with various features in common.

Abstract: Compact valve lifters are disclosed for overhead camshaft engines with direct acting valve gear and for engines with indirect acting valve actuation such as push rod actuated overhead valves. Two step variable lift and non-variable lift valve lifters are included as are roller and non-roller follower types with various features in common.