my weber didnt idle when i put it on my A14 so i pulled it apart and cleaned every single little part and jet out and put a new fuel filter and line on it from the fuel pump and this fixed the problem, and there should be an idle adjustment screw in the lower right hand side of the carby (from front of the motor )and if you screw this in it will drop the idle down but if you screw it out it will let more fuel in and will idle higher ,i thought a holley would of been more ideal for a S/C as they are easyer to tune but a weber would go better

oh and ive heard of webers needing a moulded plastic or reinforced fuel float ,because they can sometimes leak fuel into the float and will hold the needle and seat open and flood the carby
oh are you running a blow through system or a draw through ? im keen on this setup for my A14 and was wondering where you got the S/C from and how much roughly and how hard it was to bolt on /mount ?