Thanks to pages 43 and 44 of the "1950 Servicing GM Model "B" Carburetors" manual posted by Keith Hardy, I think I know what the hole is for. Evidently, it was drilled to correct a stalling, rough idling or hard starting when hot problem.
Pg 43-
http://chevy.tocmp.com/1950carb/50c43.htm Pg 44-
http://chevy.tocmp.com/1950carb/50c44.htm Consequently, I think I will temporarily plug it and see how it runs. If it does not have any of the hot problems described above, I will install a permanent plug.
Thank you Keith for sharing your manuals with your fellow stovebolt lunatics.
