Stan, once again, thanks. I don't do anything special to my carbs. The floats are dead on. The fuel pressure is exactly 3.5 psi. The linkage is also dead on, zero play. After that it's just 4 screws, set to what each cylinder needs, not some arbitrary number.
I would say that the crankfire ignition is the single best thing you can do for these old 4 cylinder lawnmower engines. It makes it start quicker, idle better and smoother. It takes out that crappy, unreliable, and INACCURATE distributor.
Stan writes with an eloquence I'll never have. This post of his should be a sticky somewhere as a must-read to anyone having "carb problems".
I've also read through that Samba thread on AFR, and it certainly took a while. But it took me to an understanding of the why and how. In short, the light came on. John Connelly supplied me with a couple 35PDSIT Solexes(with electric chokes) for a sandrail customer about 8 years ago. I also changed the distributor to an electronic SVDA and ran vacuum line to BOTH carbs. Stacked up a bunch of gaskets under a stock mechanical pump to get 1.5 psi.
I got them installed and running decent but wasn't impressed. It needed other than stock jets. I told him the engine size and exhaust and altitude the rail runs. Dead on jet sizes came in the mail. The man knows things. This rail runs pretty much like any electric-choke-equipped Big-Three single-carbed V8 back in the 70s: 2 pumps and hit the starter. It runs, warms up and idles down. It doesn't bog, spit, sputter or anything else untoward. Eight years later they haven't been touched. Still runs GREAT.
The point of that last is John from aircooled.net has more stuff in his head than a lot of people. He should be listened to when he speaks.