I've left off the vac advance on the motor, seems it ran better and was more tunable, but after reading many posts, I've decided to hook it back up. OK, Got it hooked to the ported source on the 750dp. Timed it with it disconnected, the dist. is a billet MSD, 6A box. Runs great WOT, and idles a little high, but at 3000 to 3500, the motor pops at light throttle only, I hit the gas and it stops, I thought it was overadvancing, but the plugs look perfect. Leaning out because of part throttle and light pedal? the dist. has light springs in it and all mechanical in by 2500. Any ideas?