Found your other thread in tons of fun, appears you have determined you have spark. Check valves to be sure all are moving. 180 degrees out of timie will cause backfire thru carb and coughing as well. Found that to be the problem with my 54 PO had apparently worked on it prior to my acquiring it and I replaced points etc and tried starting it with no success using his settings finally in desperation changed all wires 180 and it fired up.