I believe this to be an experimental Holley carburetor from the early development of the Model A in 1927.
I bought this carburetor from a man who said he got it from another person who got it at one of the Henry Ford Museum & Greenfield Village property dispersal auctions in the late 1980's.
It is a fact that a number of rare Model T and A items got sold at that auction including such things as an experimental X-8 engine.
It makes some sense that this may be a prototype or development carburetor because in 1927 Harold Hicks was working closely with Zenith-Detroit on an improved carburetor to get the 40 horsepower out of the Model A on the dyno.
George Holley's company had previously had the inside track with Henry Ford supplying carburetors, but was forced to compete to save the business.
A Zenith carburetor design prevailed in the end, but Holley was able to supply many carburetors to Ford under license from Zenith. This may have been a failed attempt at a Holley design for the A.
This carb is somewhat similar to some Model T carburetors, but has the distinctive Model A choke control and gas adjusting valve. It is marked as a Model 440, but I do not believe it was commercially produced.
I have never seen or heard of another carburetor like this one, and I cannot find any era advertisements for it in magazines such as Ford Dealer & Service Field, Motor, and Auto Digest of the era.
This carburetor is almost new and shows no wear. It is a very high quality of manufacture and all the parts appear much higher precision than a production Model A carburetor.
If any reader has better information on this carburetor, I would appreciate hearing from you.