44 IDF's

[Eljaro]

I do not know if the IDF's are much different than the IDA's, but I had on one body one side drawing more vacuum than the other. It had a twisted throttle plate shaft. I twisted the shaft back to to get both throttle plates in the same position both sides.
You also have to remove all the idle set screws except one. You may have some carb resting on the idle screw without you noticing and the throttle plates not closing completely on that one.
The float level is also important to check. The Webers out of the box are often misadjusted and need some attention.

[Gaz64]

race-it, listen to Eljaro, he is THE Weber guru, check out his posts.

A/F ratio with carbs has a lot to do with cam profile etc.

Valve overlap has exhaust AND fresh air/fuel mix going down the pipes, the more overlap, the more this happens.
The air/fuel going out at overlap doesn't combust very well being mixed with exhaust gas.
Leads to high hydrocarbon and high CO emission levels.

Unavoidable with carbs and big cams, more easily controlled with sequential EFI.

My V8 runs 14.2 at idle yet smells of fuel at idle and burns your eyes if you're behind it up close.