Simpl question for the right person------maybe

[harryc]

I run a regular model A distributor with modern points and condenser and 12 volts. I decided I would try a high performance coil out of curiosity. I know little of automotive electronics. When I connected the new coil my car stumbled and would hardly run. I put the old coil back on and it ran fine. I tried another time making absolutely sure everything was connected properly and had the same result. So now I am back to the older coil with my car running fine. I don't get it . Switching the coil should be simple! Could the condenser have anything to do with it? Any suggestions?