Well learn somethin new everyday. Thanks. That carburetor in question did have one though, as that diagram clearly shows. I'd sure like to know how the early AFBs that did not have the air valve fought off the horrible bog it would cause without one. I've seen a LOT of AFBs and I've never seen one without it......not that that means a thing. I'm sure if you say some didn't have them it's true, because stuff like this goes through evolution as it's evolving through time. I'd like to see one without it so I could see how they managed the bog. Maybe a tighter secondary venturi?
