Probably hearing the spark jumping inside the dizzy or cyl. since You are triggering a spark with the pick-up lead and the coil wire is back on. You've got enuff voltage that
it isn't the issue,& the starter relay is sending the system voltage cranking. They sell nice trailer harness cleaning kits now, can use them to clean the pick-up connections
nicely. As TB said, those molded dist. pick-up connectors let the socket terminals relax & open, close 'em up so they fit snug once their clean. A squirt of contact cleaner &
a little di-electric grease and You won't have to fool with 'em again unless the pick-up goes bad.