Altitude Compensator: Description and Operation

Fig. 69 Typical air jet controller:

The air jet controller, Fig. 69, is an atmospheric pressure sensing device. It controls the amount of air flow into the slow and main air jets of the primary carburetor throat, and the slow air jet of the secondary carburetor throat. As outside pressure is reduced by increasing altitude, the bellows expands to open the valve in the air jet controller, increasing air flow to the jets to maintain optimum air/fuel ratio.