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I don't know the answer but, what you did by doing this, begs the question. By closing the choke does it increase the vacuum? Can you do that and measure at the same time whether the vacuum increases to something like the 18/21" required? Just my thoughts, I'm no expert.

I was in a pretty quick hurry, i think the vacuum climbed but any intake restriction would build vacuum as long as the motor doesn't stumble, correct? I didn't pay enough attention to it to notice before putting it away.

Are you sure you dont have a vacuum leak somewhere? Is the vacuum advance working as it is supposed to?

Back to where we were about 40 posts ago - you'll never get it to run acceptably with 10 inches of manifold vacuum. The fact that it smooths out a bit when you choke it says you've got much too lean a mixture. Causes probably either a very significant carburetor problem or a large vacuum leak, much larger than just the distributor diaphragm if indeed that's leaking. A leaking distributor diaphragm alone isn't going to materially affect idle smoothness.

How about intake manifold to engine block gasketing?

I am definitely sealing at the manifold to block, but it's kind of a moot point because i'm swapping manifolds shortly anyway.

Just a couple weeks ago, and i'm not sure what's changed, i had 18 steady, but still the rough idle. The vacuum advance does work, but to test idle i had blocked off the vacuum port that feeds it and the wipers at one point, with no noticable difference.

Again, i'm not ruling out something majorly being wrong with the carb, or the jet's needing an adjustment, i just didn't suspect it with it all just being gone through.

The point i'm kind of at is that the carb and manifold are being swapped with new/different pieces, so that will show instantly if that's the problem. The new manifolds will be milled flat to be sure they seat well after being blasted, new hot spot gasket kit, powder coated intake and cast-look manifold paint for the exhaust, topped with the NOS carter 4bbl carb.

If it's not carb/intake related, the same issues should come right back to the surface after the swap.

Edit: Of course, the ignition was out of whack a few weeks ago, so maybe it was rough then from that and the carb was ok, and rough now from carb issues. When you put your hands in everything you're likely to cause/reveal some issues.

A suggestion. Saw this done on my '41 120 to "find" an exhaust leak. Take a length of rubber hose about 4' feet long and use it like a stethoscope. Hold one end to an ear and the other end to the intake and exhaust manifolds moving from joint area to joint area listening for unusual noises. What "unusual noises" are I don't know but I'd imagine after a little practice you'll be able to tell. Using this method a guy at an exhaust shop "found" my exhaust leak in the area of the hot box joint between the intake and exhaust manifolds. The leak couldn't be seen, being on the inside surface which isn't visible until the manifold unit is separated. May work for you to find a vacuum leak.

And another thought. Over the last year or so I've seen a couple of instancs where exhaust gases have blown through the bottom walls of the intake manifold hot box. The above stethoscope diagnostic should tell you if there is anything wrong in this area. And because you're going to put new manifolds on, before doing so, check this area in your new intake manifold to ensure there are no holes. Clean out all the carbon buildup on the underside of the intake hot box and poke around for thin areas. Better to find and fix now rather than have to pull the manifold off, and apart, later.