Carb issues

I've got a 340 6 barrel setup and had problems with it. Was running too rich, rebuilt carbs and still problem. Finally rebuilt center carb and blocked off end carbs (solid plates blocking off manifolds) and did the tune up on only center carb. Then added the end carbs after center carb was adjusted and ignition and timing was correct. You can't just shut fuel off to end carbs as they pull a little air in past throttle plates and won't idle. I replaced the points system w Pertronix electronic ignition too. That helped things too.