Abstract: A free standing air bleed control module is connected to an automotive downdraft type carburetor only by tubing so that it can be located in any convenient position in the engine compartment and yet provide a complete air bleed function to the carburetor fuel lines without a new casting for the carburetor; the module containing a bleed air metering valve movable by a servo to control the flow of bleed air into the fuel lines of the carburetor, the servo being controlled by a computer sensitive to engine operating conditions to schedule the bleed of air at the desired time.

Abstract: A multi-stage carburetor has a primary throttle bore that is extended into the intake manifold in close proximity to the exhaust gas heated manifold floor, and a secondary bore that surrounds a portion of the primary bore and terminates at the inlet to the intake manifold so as to avoid a restriction to flow of secondary air into the manifold and past the primary passage.