The carburetor dashpot is used to cushion the closing of the throttle. It basically allows the automatic transmission and the engine to catch up to a sudden closing of the throttle. This particular carburetor part has not been produced for several years now and are often missing from a carburetor, but Mike’s Carburetor Parts has obtained several of these recently. They are in limited supply and are a retrofit item. This means that on some carburetors the stem may have to be cut to length. You can find these dashpots here.