Abstract: The piston actuator for a governor valve in a carburetor is coupled through an electromagnetically operable selector valve to either atmospheric pressure in the air filter or to vacuum in an intake manifold. The selector valve is controlled by engine speed detected by speed detecting means, and by a switch controlled by the accelerator linkage to close a circuit whenever the accelerator pedal is depressed to within a range bordering maximum depression. When the accelerator pedal is depressed to within the above range, and engine speed is below a predetermined value, the selector valve connects to the manifold to interrupt operation of the governor valve. Operation of the governor valve resumes when the speed reaches the preset value or the accelerator pedal leaves said range.