I picked up a 22 engine that has the remains of an odd vaporizer on it. It has three operating levers; the throttle in the normal place, the choke in the normal place and a third lever just above the mixture. What is the third one for?
A bell crank for a front choke
A bell crank has two arms. This has one arm and two stops.
You have a Simmons Vaporizer. Western Auto sold it as an aftermarket Model T carburetor in 1927. It closely resembles a Ford/Holley vaporizer installed on Fords since late 1925, but it is significantly different. The lever on the vaporizer place is used to vary the degree of vaporization, or the percentage of fuel vapor that is pre-heated. In general, you were supposed to switch from 100% in the winter to 50% in the summer. The vaporizer plate is completely different from the Holley design. Instead of a thin steel plate, it is heavy, machined cast iron and bronze.
In general, the Simmons is robust and well made, all except for the choke assembly. The choke stratagem on the Simmons is simplified, and the air pipe that runs down the back of the carburetor is a dummy. The needle valve is small and fragile. A threaded vacuum-take-off is provided on top of the intake manifold.
See the attached photos.