How to Rebuild a 1932 Ford Model B Zenith Carburetor for a Model A 4-Banger Motor
Big Improvements for the Little Banger
By Ryan Manson * email@example.com
When Ford introduced the Model A in late 1927, it was remarkably different from other automobiles offered at the time, even Ford’s own Model T. In many ways, it was a clean sheet design when compared to Ford’s previous line. Many similarities abound, but the Model T and the Model A differ in more ways than they are similar. And four years later, when the Model B came along, the story was very similar. If the brass at Ford at the time were learning things as they went, it was pretty obvious that they were incorporating those things in real time. So, it should come as no surprise that as the new models came out, hot rodders borrowed parts for their older Fords. Wheels, brakes, shocks, transmissions, engines, even complete frames were common swaps for the earlier T and A models as better components were introduced on Ford’s latest offerings.
One of the early hop up techniques for the Model A was to swap to the larger 1932 Model B Zenith carburetor. Equipped with a similar, slighlty upgraded flathead four-cylinder engine, the Model B Ford was fed by a slightly larger updraft carburetor (1 1/8-inch) than that found on the Model A (1-inch). While that small difference in size may not sound substantial, it actually equates to a 26% increase in area which translates into more air and fuel that can be fed into the A engine. That small increase can yield upwards of 4 horsepower. Another inconsequential sounding number, but when added to the A’s paltry 40 horsepower, results in a net gain of 10%. Not too shabby for the 1930s!
In addition to the performance gains, there are a few reliability improvements to be had with the Model B carb as well. For starters, Ford changed the design of the float bowl on the B, going from a float that pivoted at the rear of the float bowl to one that pivoted from the side, transverse to the direction of vehicle travel. This promptly solved the “stalls when stopping” issue that plagued so many Model As at the time. The addition of a power jet circuit on the Model B carb also resulted in a smoother transition from off-idle to wide open throttle settings thanks to an ingenius design that siphoned fuel from the float bowl at varying throttle openings, enriching the mixture at open throttle conditions similar to an accelerator pump but without the linkage or diaphragm.
Upon researching the benefits of the Model B carb and with a stock Model A Zenith carb that leaked while parked and stalled while stopping, I decided to set out to find and install a Model B carb on my ’30 coupe. Once a usable core was located, I ordered up the necessary gaskets, fuel fittings, and a set of flowed jets from Renner’s Corner in anticipation of splitting the old carb in two and putting it back together, better than new. The result is an old car that fires right up, doesn’t stall while coming to a stop, and smoothly accelerates without hesitation. It doesn’t leak when parked anymore either, which is an added bonus!
So follow along as we breath new life into an 88 year old carburetor to improve an 90 year old car by rebuilding that old Model B Zenith carb! CC
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