first you do need a good working dizzy, the stock points will not do it for your set up. second webbers are sensitive to weather cams etc . I usually do all my work but I had a difficult time sycronizing the carb especially with a the cam I had, i though I finally had it right so one day I went to Z meet and we were talking about our cars and a person name Bob dimaggio walked by and said your carbs are not right you must have falt spots, he tune the carbs it took him 15 mins and I can not tell you how fast smooth my car became. Latter I found out that Bob raced the 240s had a shop etc. Moral of the story it is difficult for us to tune carbs at idle with a cam unless we have done them for many years and many times .