Curse of the 1920?

Hey all:

My 1973 Valiant has 49,000 verified miles on it, and still possesses it's original 1920 carb complete with functioning idle dashpot(it's a manual trans).

I'm 99 percent sure it's never been off the car based on the thickness of grunge on it and the original owner saying it hadn't. The ears on the float bowl are unbent too, lol.

It's doing something weird:

It starts easily with the automatic choke, idles down in steps as it warms and idles fine after the choke comes off. However, if you switch off the engine, let it sit about 15-20 minutes, you can't get it started without holding the pedal part of the way down.

Once it starts, it will not idle. It chugs down and sounds like it loses a couple cylinders, then quits. Next day, it starts right up.The choke is WIDE OPEN during this episode, so no need to even mention the choke.I did adjust the valves, only had to loosen a few.

So, does this sound like something familiar with one of these?

I'll end with saying that I dislike these carbs. I know some people profess to love them, but I've seen a lot more that didn't run right than I ever have that did. On top of that there are two major potential leak points right over a hot manifold. On top of THAT, there no more floats to be had and the metering block can't be cleaned all the way. Why does anyone want to fool with one of these things?

Thanks for reading.