I can clearly see in your picture that the cable housing is all or most of the way forward , so there is a 7/16 nut on the bracket , slide the housing as far back as possible without opening the carb .
The Weber carb is a Edelbrock copy of the old AFB Carter carb , these are one of the worst carbs available,[ probably the 1406] , the original AVS is what Mopar originally used , Edelbrock also copies that carb as the Thunder series , the AFB is one of the least tunable carbs available , but will usually get the car around under its own power , the Thunder carbs are somewhat better .