A modified carburetor allows the fuel and air input ratio to be adjusted by varying the opening sizes in the carburetor. After the proper air opening size is determined and set, the fuel jet setting can be adjusted for cold starts and/or to fine tune the engine. The air opening setting may remain the same, regardless of engine speed. This allows the engine to create a vacuum of near zero to five inches of mercury or more, depending on the speed of the engine. A small air input opening setting may be used for the engine to create this vacuum. The higher the vacuum created, the better the fuel efficiency. The fuel from the modified carburetor then flows through a heated evaporator chamber that maintains this vacuum. This enhances and completes the evaporation process as the fuel passes through and over metal shavings toward the engine.