The invention improves volumetric efficiency of the internal combustion engine. A suspended cam, 1, follows a limited arc of rotation about the axis of a drive gear, 3. A change in engine speed (r.p.m.) activates the hydraulic piston 8, and alters the cam heel position along this arc that is tangent to a cam follower, 9. The separation distance, between the cam follower and cam heel, determines the duration of valve opening. The separation distance and the rocker arm ratio control the amount of valve lift. As the cam axis sweeps across the cam follower, there is coordinated movement of the cam follower fulcrum, 11. This tempers the otherwise excessive change in rocker arm ratio as the cam contact point on the cam follower moves in the "x" direction with rotation of the suspension assembly, 2. The rotation of the cam axis and gear reduction assembly, 4, 5, & 6, about the drive gear, shifts the timing of cam contact. This timing shift creates a desirable asymmetrical expansion or contraction in the duration period of valve opening.