OK here's my 2 cents, if the motor is in good shape, a down draft weber can be tuned to run well, but remember it's a progressive carb, meaning one barrel is open and one opens at 60-70% of throttle, it's not a performance carb. It's a good all around driving carb. Good mpg. The problem is when the motor is starting to wear or something else is not right the Weber is not forgiving and will run like shit.

Su carbs are more forgiving when a motor starts to wear, and when properly turned run better then the Weber for spirited driving. But the SU must be looked after, like check dash pot oil, if you drive in cold weather then a minor adjustment should be done in fall, and again in the spring.

If given a choice, I would install SUs, but if no choice I can turn Weber's, but if your motor is worn out I won't waste your time or mine. If your running a 75 or later B with its stock motor with over 55 k miles on it, then putting on a Weber is a waste of money and time, due to cam failure. Most MGBs with over 65k suffer from head gasket and cam failure of some degree.

So there's my 2 cents

George Van Horn
USN            Ret.
 
USS Virginia CGN-28
USS Wainwright CG-28
USS Monterey CG-61
USS Ross DDG-71