Abstract: An apparatus for controlling the flow of air in a conventional venturi-type carburetor. A small tube and a large tube connected by a tapered transition tube is placed inside and concentric to the venturi of a carburetor with the large tube being closer to the throttle valve of the carburetor. The cross-sectional area of the large tube should be in the range of two to three times that of the small tube. A collar or draw plate is mounted around the small tube to control the air flow in the passageway formed by the outside of the wall of the small tube and the interior of the venturi. An aperture is provided in the peripheral surface of the small tube to permit the main fuel-metering nozzle of the carburetor to extend into the interior of the small tube. Small air bleed holes may be provided in the peripheral surface of the apparatus to permit the travel of gaseous materials between the exterior and the interior of the apparatus.