Ed - information on Zenith. Zenith, as well as Carter, Rochester, etc. made carburetors in standard S.A.E. sizes. The sizes normally of interest are:
Size 1 - Nominal 1 inch carburetor with center to center mounting bolt spacing of 2 and three-eighths inches
Size 2 - Nominal 1 and one-fourth inch carburetor with center to center mounting spacing of 2 and eleven-sixteenths inches
Size 3 - Nominal 1 and one-half inch carburetor with center to center mounting spacing of 2 and fifteen-sixteenth inches
Example of size 2 would be a Carter W-1 from a 1941 through 1949 Chevrolet, or a Rochester B for a 216 Chevrolet. Example of a size 3 would be a Rochester B for a 235 Chevrolet.
Zenith also built each size in a style A or B. Type A has the throttle shaft and choke shaft in the same plane (if you look straight down the throat of the carburetor, you will see the choke shaft, but the throttle shaft would be "hidden" by the choke shaft). Type B has the throttle shaft and choke shaft perpendicular or crossing each other.
Within each S.A.E. size there may be 5 to 9 different internal venturi sizes (the venturi is the major determinent for airflow capacity).
There is NO universal hot rod carburetor. For best results each application should be planned for S.A.E. size (manifold will determine this), internal venturi size, and type. Generally, linkage can be fabricated to use either type, but some applications work better with one type.
The Zenith 9046 which you mention may have been in "vogue" at one time due to availability. This carb was used on a military application, and often the military over-purchased and items were then sold off at a fraction of original cost through military surplus. This carb would never be my first choice for a hot-rod installation.
If anyone wishes help in selecting carbs for a multi-carb setup, feel free to call me at the shop during normal business hours.
Jon.
