The carburetor was in production for only about four years, but it's amazing how many little design variations were implemented in that time.
How the Carburetor Design Evolved
- The design was tweaked in many ways from 1927 through 1931. The more significant ones will be described here. Some of changes occurred after Zenith lost a copyright case brought on by Stromberg concerning the double Venturi design. A single Venturi design was introduced in July of 1928. At the same time they added a brass secondary well, changed some jet sizes, and reduced the length of the idling jet. Around February / March of 1930 a number of small changes were made, including changing some of the orifice sizes again. Pennsylvania enacted a law prohibiting the location of gasoline shutoff valves inside cars. This law forced the relocation of the shut off valve from under the dash to the engine compartment firewall in mid 1931. Now, the shutoff valve interfered with the location of the sediment bowl. A change was made in the carburetor upper casting to add a sediment collector to the carburetor. This design change became known as the "Side Bowl" Zenith.