Assuming you haven't tried shifting it manually, I'd try that and see what happens. I don't know a whole lot about transmissions (OK, maybe not about a lot of stuff
), but if it runs fine except when it's shifting, I'd start by testing it to make sure it runs well every time it isn't shifted by locking it into 1st gear and taking it up through the rev range and seeing what happens. If it runs fine regardless of rpm, load or throttle position, that should eliminate a fuel delivery problem caused by a faulty pump or a blocked filter. If it doesn't, then work on diagnosing the fuel problem.
If it's not a fuel delivery problem, I'd manually shift it from 1st to 2nd and see if the problem returns, making sure to check at different throttle positions. Is it more prone to stalling under light load and low speed shifts or under heavy acceleration and high-speed shifts? If the stalling problem comes back, I'd look for a problem with the throttle linkage to the transmission that might be causing a problem at the carburetor. Maybe when you re-installed the carb, the linkage got out of adjustment and is now binding or moving in ways it shouldn't. Or, possibly, now that you've got it running and driveable, this is a problem that was there all along, but couldn't be uncovered without it being on the road.
By way of example, two weeks ago at work, we had a bus that was having a problem with very hard shifts and it sometimes wouldn't downshift while slowing and would stall at lights. It was one of those things that would happen intermittently - I went on two 30 minute test drives and it drove just fine. We had just installed a new engine and automatic transmission that required some pretty intensive modifications, a mod we had already done five times before with very few problems, but no one could figure out what the problem was. Finally, my boss called in a heavy-duty transmission tech to help diagnose the problem. Reportedly, he got under the bus and looked at some linkage that would allow the transmission to downshift as the speed slowed and some part of it was loose and was binding and not allowing the transmission to downshift or the torque converter to unlock when the bus was stopped, essentially turning it into a manual transmission. The problem was that the part was small and wasn't always binding up, so sometimes the trans would operate normally and other times it wouldn't. (I'll get the proper terms in here tomorrow.)
Just my
Going back to watching now. Good luck!
