Abstract: An automotive type carburetor has a rotatable lever connected to the choke valve and to an actuating link having a pin-slot type connection to an engine vacuum controlled servo, a fast idle cam is connected to the choke lever by a lost motion pin and slot connection and to a second actuating link also connected to the servo by a pin-slot type connection, the servo pin-slot connections to the links are such that when the engine is started with the choke valve closed and the fast idle cam on its high cam step, vacuum applied to the servo during a first stage movement rotates the choke lever to open the choke valve and subsequently during a second stage movement both the choke lever is rotated further and the fast idle cam is rotated off its fast idle step position, to reduce the opening of the throttle valve while opening further the choke valve, the first stage movement of the servo moving a diaphragm and plunger until the plunger blocks a main vacuum feed line to the diaphragm, the second stage movement movin

Abstract: A variable area venturi carburetor has a movable venturi wall with a fuel metering rod attached for cooperation with a fuel jet located near an opening in the fixed venturi wall portion, a bypass passage connected to the connecting chamber between the fuel jet and the wall opening siphoning off the fuel at closed positions of the throttle valve to prevent stumbling of the engine by fuel flowing into the main venturi and clogging the small clearance space between the throttle valve and induction passage wall.