a device for selectively disabling and enabling , while running , the combustion chamber valves of an internal combustion engine . the device is interposed in engine valve gear of the type employing a plurality of rockers mounted on a common shaft and acted upon by the cyclic application and relaxation of valve gear driving forces . each of the rockers is pivotally mounted on the shaft by fulcrum means movable transversely with respect to the shaft for changing the rocker pivot point . the fulcrum means is mounted by latchable means movable , when the valve driving forces are relaxed , between a first and second position to permit changing of the rocker pivot for effecting disablement and enablement of the valve gear for selected valves . actuator means selectively apply and hold a force on the latchable means and movement thereof occurs during the valve gear event upon relaxation of the driving forces .