Abstract: A carburetor includes a base, a Venturi cone assembly, a cam assembly, a horsepower adjustment assembly, and a vacuum horsepower adjustment valve. The Venturi cone assembly is mounted in the base. A supporting portion of a cone collides with a cam of the cam assembly. An oil line rotation wheel of the horsepower adjustment assembly is drawn by an oiling line to drive the fan blade. The amount of displacement of the cone of the Venturi cone assembly under vacuum suction from the engine is controlled by a cam of the cam assembly. The vacuum horsepower adjustment valve automatically supplies enough fuel to the engine. Accordingly, the present invention can make the fuel burn sufficiently, effectively improving efficiency and reducing air pollution.