Float can be out of adjustment or float itself could have pin hole and will never work right......float needle could be wore out replace with grose jet way better.... replace fuel filter or add one inline before carb to keep crap out of the float chamber..if fuel pump has been replaced recently could have too high of pressure..mixture needle could make it run rich but doesn't usually severely flood the car like you are describing.....if choke gasket is leaking it can cause flooding....choke out of adjustment or it's internal parts aren't working right could cause flooding....I've had an mgb catch on fire because of a flooding problem carry a fire extinguisher...mgbss63