A bit more information on Zenith and Stromberg:
First, I am amused at how many try to put any carb on any engine and then tune it
Why?
I have posted many times about the S.A.E. carburetor sizes, and I think by now most that read these forums are familiar with these. BUT STROMBERG AND ZENITH FELT THESE WERE NOT ENOUGH SIZES!
So, both Stromberg and Zenith have "in-between" sizes.
If you look at the Zenith type 228, you find the size 2 might be a 228AV10, whereas, the size 3 might be a 228AV12. (A (B) replacing the (A) is possible in both cases, showing the throttle and choke shafts are perpendicular rather than parallel.
But Zenith also provided "in-between" sizes as did Stromberg. So a Zenith 228AV11 would have a size 3 bolt spacing, but a throttle bore about halfway between the size 2 and size 3.
Stromberg also provided in-between sizes, and these are specified with an "O" or a "U". The "O" is an oversize throttle bore, the "U' is undersize. So a BXUV-3 carb will flow less than a BXV-3 carb with the same venturi. Conversely, a BXOV-2 will flow more than a BXV-2 with the same size internal venturi.
And while the internal combustion engine is incredibly flexible, there really is an optimal size carburetor for each engine.
Jon.
