Abstract: An improved direct acting hydraulic valve lifter (DAHVL) has features including reduced dead oil storage with lower mass and faster filling, improved air venting, internal oil recirculation and targeted oil supply that combine to reduce the presence of air in the lifter. Foam filling and baffle reconfiguration are included among means for reducing stored oil volume which can also improve the follower cylinder support. Means for venting along the piston and cylinder of the lifter are shown. The various features combine to limit air intake and to more quickly expel air which does enter the lifter.

Abstract: Low mass hydraulic and mechanical valve lifters are shown and described. The lifters are of oblong configuration for reduced mass, with straight or narrowed sides connecting longitudinally spaced ends having depending semi-cylindrical end walls that are received in similarly shaped end portions of lifter gallery openings to absorb all longitudinal and lateral side loads. The lifters are preferably made by investment casting of steel alloys. The investment casting permits the use of thin semi-cylindrical walls at each end of the valve lifters which also have internal reinforcing ribs extending on their undersides.