Abstract: A valve actuator having a pivotal cam-lever driven push-pull mechanical linkage system. A power mechanism moves a cam-lever member which then moves a connecting rod to move a push-pull member to lift out or push in a conventional valve stem. This then opens or closes the valve. In an alternative embodiment, the actuator includes an adjustable block member to which the cam-lever is pivotally attached. This provides a separate adjustability for the ultimate maximum movement of the push-pull member and thereby also of the valve stem in order to ensure a proper closing force is imparted to the valve. Also in this embodiment, it is preferred that the push-pull member includes at least one spring washer disposed therein. This provides a desirable compressibility in the system during the imposition of the force that the push-pull member exerts on the valve stem during the opening and/or closing process.