I still had the flow wrong. The choke is fed off the same place as the heater. There's a tee there, with the heater feed hose and a smaller hose that goes to the choke. After the choke, a hose feeds the carb base. From there it exits the intake manifold and enters the metal tube around the back of the engine and returns to the water pump. So, it wouldn't really matter if the small passage between cylinders three and four was eliminated by Clearwater, since most of the coolant makes its circuit independently of that anyway. Dang.

It's almost light enough to see outside so I'll go take a look at the choke with the air cleaner lid off. Having the choke remain closed after warm-up would almost be too easy now, it seems.

Any other ideas?

John B.