An improved carburetor for an internal combustion engine is disclosed. A mixing chamber with means for creating air turbulence and improved homogenization of the air-fuel mixture is provided. The disclosed carburetor comprises a lower portion having an opening adapted to be connected to the suction side or inlet of the engine, a partially closed compartment provided with a cover, a valve regulating the air passage through this opening and thus transmission into the compartment of the reduced pressure produced by the suction effect of the engine, and a set of pipings forming an arrangement of fuel lines adapted to be connected to a fuel supply and having fuel distribution means arranged for adding, in an appropriate manner, the homogeneous air-fuel mixture necessary for each running speed of the engine. Improved combustion and lower level of noxious emission gases are effected.