I have a 1948 8N that has been converted to 12 volt negative ground with alternator. I have 1247XT Pertronix electronic ignition. It tan fine until recent engine rebuild. Upon reinstalling engine i am having trouble with ignition so am entirely replacing it with new 1247XT and new coil. Summit Racing is telling me if i use their Flamethrower coil w/3 ohm internal resistance, i donít need ballast resistor. I have read Bruce Haynesís posts on this subject and his 75 Tips For N Owners Based on what i read there, Summit Racingíís advice does not sound correct and coil will overheat with high resulting amperage. Is it?