In 1923, Chevrolet went out for bids for carburetors. One of the provisions of the bid, is that Chevrolet would be allowed to build a certain percentage of their needs themselves.
From all I can read, Carter was the only company that would comply with that provision.
So Chevrolet started buying Carter carbs exclusively about 1925 (before this, a number of different brands were used, to include Detroit Lubricator, Holley, Marvel, Stromberg, and Zenith).
Chevrolet used only Carter carbs through 1949.
In 1948, Chevrolet asked Carter for a major redesign of the W-1 being used by Chevrolet.
In 1949, Rochester started producing "carburetors" (the model AA used by Oldsmobile, and thankfully discontinued after 2 years).
Since Rochester is a division of GM, GM required Chevrolet to start using the Rochesters in 1950 on both the 216 and 235. After the redesign, and then 1 year only sales, Carter was less than happy about this development; and started making aftermarket type YF carburetors designed as a bolt on replacement for the Rochester B. Many folks (including me) feel the Carter YF is vastly superior to the Rochester B.
I do not know why O.E. Carters were sprinkled into the mix from in 1965.
Jon
