Abstract: A fuel-air metering system functioning according to precise flow and geometrical equations. An air throttle valve and fuel valve are positively linked with the flow crossectional area of each valve proportional to that of the other. Fuel pressure drop across the fuel valve is regulated in precise proportion to the pressure drop across the upstream orifice of a two orifice in series air flow system which bypasses the air throttle. Careful shaping of the air throttle, the bypass system orifices, the fuel valve, passage geometry, and the servo valve fuel regulation system results in an accurate porportioning of fuel flow to air flow.