Strombergs as delivered are emissions carbs. They are designed to run lean, have bypass and temp compensation valves, and had plugs and fixed needles to prevent you from easily adjusting them. These are very tricky to set up even when you know what you are doing, and seldom stay in tune long. Switching over to Euro needles, adjustable dashpots, and disabling the funny valves makes them easy to set up and very reliable (change the needle jet while you are at it). Converted lots and lots of TR6s, late MGBs, Spitfires, late Midgets, and, yes, Lotuses. Ran just fine after that.
People and adjustment screws are a dangerous combination. SUs, Strombergs, DCOEs, bike derailleurs, whatever, show someone an adjusting screw and they will turn it. 99 times of a 100, it didn't need turning and they have made it worse. I synced and tuned 100s of cars that had been twiddled with by their owners.
