Even if the idle mixture screw was all the way in, there still isn't enough vacuum signal in the secondary vent to pull gas through it...

I'm saying the idle screw is open just enough to bypass the idle circuit.

I'm sorry, I see what your saying, but Kostya was saying the fuel mixture screwed in all the way still dribble at idle...... it will still flow gas when the fuel is screwed in lean and the throttle open.

Ok, lets clarify. If the idle screw is out all the way, this is the lowest idle speed acheivable. If you screw it in the idle increases. If there is a balance tube involved, and I'm not sure about webbers, the other carb is gonna compensate somewhat for the lack of performance. If it dribbles, and never fills the throat with gas, that means the butterfly is open, mabey a fraction of an inch. The butterfly isn't closing completly because of the idle screw being screwed in to much.

Mabey I'm overthinking things......What is known: The carbs do not have linkage hooked up. The passenger carb dribbles gas at idle. The car won't idle with the linkage disconnected.
Questions: Is there a balance tube between the 2 intakes? Will the car idle with the linkage installed?

From what I can guess, the car ran with the linkage hooked up, before pulling the motor. Reinstall motor and run it with out linkage and it won't idle. Notice gas dibbling in the passenger carb at idle. Is this correct?

The car WILL idle with the carbs disconnected. The passenger side carb dribbles gas, whether the mixture screw is all the way in, or all the way out.

So, what "symptom" made yall look into the carbs of a running car? Just curious, or was the car running weird?

He said that it would drive ok, but would stall when coming to a stop, and then wouldn't run right. I had this problem last week, with the right bank being flooded due to a bad float, but this isn't the case in his car. And gas shouldn't be dripping from the main circuit venturie either.

I've had this problem before in my car. It was the linkage not moving the throttle arms in sync. What I think is happening, like it happend to me, was when coming to a stop sign or idling to a stop. The carb throat fills with gas and "chokes" the motor on that side causing it to stall. The linkage needs to be set up so that when you step on the gas full throttle both throttle arms hit full open at the same time. Then you remove the linkage, adjust the fuel mixture. Reconnect the linkage and the sync the carbs using a snail. To sync the carbs you adjust the air mixture screw until the carbs are pulling the same amount of air. Do you follow? Because of the linkage settings being off before syncing the carbs, the air screw is too far out on the one carb, causing it it to flow fuel at idle.