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 carburetor has a vacuum servo that actuates a rotatable cam member to automatically rotate the fast idle cam off its high cam step engagement with the throttle valve adjustable idle stop screw while at the same time opening the choke valve to both lean the mixture and reduce mixture volume, for better emission control than when manually controlled as in conventional constructions.