Dual Carbs

Source:  http://www.modelaparts.net/webbcat.htm/catp63.htm

Stromberg and Zenith Carburetors

Stromberg did indeed bring a patent infringement case against Zenith (Stromberg Motor Devices Co. v Zenith-Detroit Corp) alleging that Zenith’s double-venturi carburetor was an infringement on Frank C. Mock’s patent (U.S. Patent No. 1,404,879) which had been assigned to Stromberg.

Stromberg prevailed at the trial court level (U.S. District Court for the Southern District of New York) as well as (on the infringement claims at least) when the case was appealed to the Second U.S. Circuit Court of Appeals [23 F.2d 62 (2d Cir 1934)]. Interestingly (or not) the appeal was made by Stromberg (the prevailing party at the trial court level) because they objected to offsets of some $144,437 allowed Zenith by the trial court against the $421,497 in profits Zenith was deemed to have received by its unauthorized use of the Mott patent, resulting in a net award to Stromberg of only $277,060 (which, at the height of the Depression, was still a tidy sum).

This was not the first time (and may not have been the last) that Stromberg sued Zenith for patent infringement. During the Model T era (Stromberg Motor Devices Co. v Zenith Carburetor Co. [254 F. 68, 69 (7th Cir. 1918)]), Zenith was found to have infringed on four patents held by Stromberg.

None of this has much to do with making your Zenith carburetor work more effectively, but the original case mentioned above has reverberated through the legal system and is frequently cited in allowing offsets of federal taxes paid by a losing defendant (e.g., Zenith) on their ill-gotten profits where such patent infringements are made in “good faith” (i.e., non-willful) instead of being conscious and deliberate infringements.

Carburetor Idle RPM and Idle Air Mixture Adjustment

Carburetor Idle RPM and Idle Air Mixture Adjustment

1. There are two external carburetor adjustments, and they affect only the idle performance. They are the idle RPM and idle air mixture adjustments
2. Turn Gas Valve under dash on passenger side to open (Pointing down)
3. Preparation: Fully warm the engine up, move spark control (on left side of steering wheel) up, turn the under dash choke control knob full clockwise and then counter clockwise about one turn, and move the hand throttle lever (on the right side of the steering wheel) all the way up. If engine tend to die, pull the throttle lever down a little.
4. Preliminary Idle RPM adjustment: Turn the adjusting screw on the carburetor throttle arm until the end of the threads is making contact with the stop. You should now be able to put the hand throttle lever all the way up without the engine tending to die. Go back to the adjusting screw on the carburetor throttle arm and adjust it to a low RPM, just faster than where engine tends to stall. This will ensure that the carburetor idle circuit if functioning.
5. Idle Air mixture adjustment: Slowly turn the idle air mixture screw clockwise until the engine begins to stall, and note the position. Slowly turn the idle air mixture screw counter clockwise until the engine begins to stall and note the position. Now, adjust the screw about half way between the two positions, and you will often hear a very slight increase in engine RPM. (Idle air mixture screw should be about 1–1/2 turns out from full clockwise.)
6. Final Idle RPM adjustment: Pull the spark lever about 3/4 down. Readjust the idle RPM adjustment for the idle speed that you prefer. (If adjusted too high, you will likely tend to grind gears when driving.)

Source: http://www.model-a.org/procedures_full.html