Adjusting carb mixture control?

[MikeC5]

I'm trying to get my '25 engine running properly (it hadn't been started since 1948 I as told). I rebuilt the carb (even sprung for a new float), adjusted the valves, rebuilt the vacuum tank, verified good compression (50-55 psi all). The engine starts easily with hand crank (running on battery). Vacuum measures between 18 and 19 inches at brisk idle. The problem is that it will stall unless I leave the mixture control enrichment on (maybe 1/4 of its total rotation). Even with the adjustment screw turned down all the way it won't stay running. I let it warm up for 10-15 minutes and I was able to back off some but not all or it would stall again. I tried tapping lightly on the carb body in case the metering valve was stuck but it didn't change anything. Any clues?

One thing about the carb, I did not have (or make) the tool needed to take the metering valve apart. I soaked it in lacquer thinner for a day and sprayed it out good but? Any clues would be welcome..