Bizarre problem, that's contagious...

[rosenkranswa]

Some years ago I started having an annoying problem with my '30 AA Stakebed. It would start fine with the GAV maybe halfway open, warmup allowing me to close the GAV down to less than a quarter open and idle nicely. But, when I got on the road it would act like it was way lean, and wouldn't run well until I openned up the GAV almost a full turn. Then I would have to leave it there with it running slightly rough at stop lights.

Tried retiming, cleaning and regapping plugs, reset point gap, cleaned carburator, checked for air leaks at the carb and manifolds; nothing seemed to work.

Just figured I'd have to live with it, then my '30 pickup started doing the same thing. Tried all the same remedies to no avail. The '29 Roadster was next, and now the '31 Woody. Same symptoms, same remedies, same outcome. The Woody is the worst, once warmed up I have to open the GAV almost a full turn to run, then when at a stop it runs real rough until I turn the GAV down to less than a quarter turn open, then have to open it again once I'm moving or it acts over lean.

I'm at a loss, what could be affecting all 4 vehicles the same way? Am I doing something, or are they all reacting to something in the local gas?
The '30 Town Sedan and both Model T's don't seem effected - yet. Ditto the early V8 and wartime Jeep.