Well, its Sunday afternoon, and I have lost my focus (messed up some kit components I was making for ancient Buicks) so have quit for the day.
So will add a bit of Chevrolet carburetor history. If I bore you, just don't read it
Before 1923, Chevrolet used carburetors from a variety of manufacturers. In alphabetic order: Carter, Detroit Lubricator, Holley, Marvel, Stromberg, and Zenith (mostly Zenith).
About 1923, Chevrolet issued a "bid" for a carburetor supplier. Part of the bid specification was that the successful bidder would allow Chevrolet to manufacture a certain percentage of the annual usage in their Bay City plant. Supposedly, Carter was the only company to agree, and thus won the contract.
Carter was the primary supplier in 1924 and 1925 while Chevrolet used up the remaining Holley and Zenith units, and beginning in 1926, Carter was the exclusive supplier to Chevrolet through 1949.
Carburetors produced in the Bay City plant had a large "C" cast on the side of the cast iron. These carburetors, while almost identical to the Carter versions, carried a tag with the Chevrolet part number rather than the Carter number; and the internal parts that were stamped, were stamped with the Chevrolet part number.
In 1948, Chevrolet asked Carter to redesign the W-1, adding a basic fast idle, which was really a hand throttle that was used in conjunction automatically with the choke. This feature appeared on the 684s for 1949 on both passenger and truck, and in 1950 on trucks with 216's only (no passenger).
In 1949, Rochester started building carburetor, beginning with the (opinion) horrible type AA, which thankfully lasted only 2 years.
I do not know the source of the order, but Chevrolet stopped buying Carter for passenger vehicles in 1950, and trucks (other than C.O.E. models) in 1951. Remember, Rochester was a G.M. company.
Chevrolet also added the Rochester type B as a factory service carb for 1937~1949 vehicles.
Naturally, Carter was less than thrilled about losing a customer particularly after redesigning the carburetor for the customer.
As Carter now had the YF carburetor, the CEO of Carter order direct bolt-on replacements to replace the Rochester B, and swore they would sell 1 million of these!
Rochester made a two-barrel version of the B (the BB), (opinion, also horrible) but fortunately, it lasted only a single year!
The Carter YF had a very successful run, being used from 1950 through 1985.
Jon
