Abstract: A cylinder deactivation device includes a stud rigidly engaged with the head of an internal combustion engine, a rocker arm, a rocker ball, a stand element attached to the upper end of the stud, a cylindrical sleeve having an inclined slot in the wall thereof, a peg slidably disposed in the inclined slot and extending through a cylindrical hole in the fixed element, and a compression spring for exerting a constant force urging the rocker ball against the rocker arm. The cylindrical sleeve is rotated to control the elevation of the sleeve in order to force the rocker ball to function as a fulcrum for the rocker arm or to allow the rocker ball to yield to the rocker arm. In one embodiment of the invention, the slot is L-shaped.