My #1&2 cylinders are running way rich. 3&4 are normal. Compression is 155-158lbs. on all four. I've adjusted the carbs, dismantled and cleaned them, centered the jets, set timimg, changed position of ignitor magnet ring, changed plugs, wires,and dist. cap. It runs very rough at idle and I can disconnect the #1 plug wire with no change. I checked to make sure the plugs are all firing. The first two plugs become black and sooty very quickly after cleaning. Do vacum leaks, such as throttle shaft or vacum advance fittings create overly rich or lean conditions on the SU? Any tips? Thanks