Very interesting and helpful information, thank you. It explains a lot of the issues I have been experiencing. I've been going nuts trying to fix the problem with just changing the jets. My Weber hesitates when I give it throttle rapidly, and my mixture reading on my wide band rarely stays consistent. I knew I had the T plate too far open but I couldn't get it to run well any other way. Even then it vibrated pretty bad at idle and I still had the balance shafts in my motor. It wouldn't idle smooth below ~1000 rpm. Could it be possible I need to adjust my secondary throttle plate further open before I begin drilling out the primary? I never knew it would take so much effort to set up this carb, I naively thought It would be ready to go out of the box.

Good to know the cylinders don't get even mixture, when trying to read the spark plugs I was always confused with their inconsistency. Makes sense now.

The mileage and performance you are getting with that multi carb setup is very impressive, makes me want to get one some day when I have more money. Your 72 Colt sounds like an awesome ride. Too bad they still use salt on the roads up there instead of something less corrosive, part of me thinks its just to get people to keep buying new cars...