Abstract: Carburetor for mixing air and fuel for internal combustion engines having fuel spray tube extending into throat to produce air/fuel mixture for combustion. Valve assembly has two similar sliding gate valve members which slide transversely across throat equal amounts in opposite directions and cooperate with tube. Fuel metering means coupled to valve members meters flow of fuel through fuel spray tube in amounts proportional to valve opening. In preferred embodiment spray tube has air bleed and discharge jet means spaced along tube which communicate with mixing manifold within tube and are closed concurrently by valve members as valve members approach each other. Air bleed jets admit air into fuel spray tube which mixes with metered fuel in manifold to form primary rich air/fuel mixture which discharges to produce desired leaner mixture.