There are two different type air valve dash pots used in the Quadrajet carburetors. Their primary purpose is to control the opening rate of the air valves and prevent secondary discharge nozzle lag. They also act as a dampener to prevent oscillation of the air valves due to engine pulsations.

The early type dash pot consists of a piston which operates in a fuel well adjacent to the float bowl. The piston stem is connected to the air valve through a link and lever assembly. As the air valves open, the dash pot piston is pulled upward forcing fuel to flow between the side of the piston and fuel well which retards the air valve opening. A rubber washer attached to the piston stem acts as a check valve. During upward movement of the piston, the rubber washer seats and forces all fuel flow around the piston. When the air valve closes the check valve unseats and allows fuel to also pass through the center of the piston allowing the air valves to return closed rapidly.

The last type air valve dash pot operates off of the choke vacuum break diaphragm unit. The secondary air valve is connected to the choke vacuum break unit by a rod, to control the opening rate of the air valve.

Whenever manifold vacuum is above approximately 5” - 6” Hg, the vacuum break diaphragm is eated (plunger is fully inward) against spring tention. At this point, the vacuum break rod is in the forward end of the slot in the air valve lever and the air valves are closed.

During acceleration or heavy engine loads, the manifold vacuum drops. The spring located in the vacuum break diaphragm overcomes the vacuum pull and forces the plunger and link outward which in turn, allows the air valves to open. The opening rate of the air valves is controlled by the calibrated restriction in the vacuum inlet in the diaphragm cover. This gives the dash pot action required to delay air valve opening enough for efficient fuel flow from the secondary discharge nozzles.