A properly restored Rochester B will work fairly well, and will do so for a few years. The problem lies in the cost of restoration.
The major area of concern is the lack of airhorn to bowl screws (4). As there is too much distance (or too thin a casting) between screws, the airhorn will, in time, warp. The zinc alloy becomes malleable (sp) during heating/cooling cycles, and the pressure causes the warpage. As the vacuum passage controlling the power circuit must be sealed at the mating surfaces, this warpage causes an internal vacuum leak at the power circuit causing the power circuit to always be on. To eliminate the warpage, the restorer must use heat and pressure to form the casting back to trueness.
The Rochester B is not the only carb to suffer from too few screws. Carter's first W-1 (1932 Chevrolet) had a similiar problem. However, Carter acknowledged the problem changing from 4 to 5 screws after 2 years, and from 5 to 7 screws after3 more years. The Stromberg model 97 also had this problem, but when Stromberg changed from the E series to the A series carburetor (after 3 years) the problem was corrected. The Rochester B went from 1950 to 1966 without correcting this problem.
Contrast that with other Rochester products. The first Rochester 2-barrel was the AA series of 1949. This series was modified in 1950, and scrapped in 1951 in favor of the BB (a two-barrel version of the B). The BB lasted 1 year!!!!! and was scrapped in favor of the G series (one of the finest 2 barrel carbs ever made!).
Also, as Josiah mentioned, the float buoyancy is marginal.
The B can be made to work, but the Carter is just much easier to make to work; and the Carter also is much easier to modify if the engine is modified. The biggest problem with the Carter YF is the diaphragm type accelerator pump. These can give problems in vehicles which are rarely started.
Jon.
