Abstract: A fuel-air proportioning and mixing system for internal combustion engines is disclosed comprising a variable orifice for measuring the volume of air and a motor driven variable volume displacement pump for measuring and atomizing fuel. Changes in size of the variable orifice in response to variations of air volume furnishes energy to modulate the fuel supply to predetermined ratios with continuous correction for air temperature, humidity, and barometric pressure. Electric motor also provides energy to atomize the fuel and mix it uniformly with air passing to engine intake manifold. The fuel-air ratio is controlled from the most economical to the most powerful in response to engine output load.A variation of the device to accommodate stratified charge engines provides two air fuel ratios -- an ideal mixture for ignition, and a lean mixture automatically variable with torque requirements for the main combustion charge.