New Weber Carb flooding

I have a 1977 MGB that when I got it, had a Weber Carb. The weber carb that was orginally on this MGB was constantly flooding out and made it very hard to start the vehical. This carb was very old so I replaced it with an orginal Zenith Carb. The Zenith carb was very old and in bad shape. The only thing I done to it was cleaned it up. It ran very well on the vehical and the flooding problem was gone!! Recently I bought a Brand New Weber Carb for the vehical, guess what? This brand new Weber carb is doing the exact same thing as the old one done...constant flooding...and now the vehical won't start. Any Ideas?!!! Thanks