Spark plug gap

The mag is not putting out that much current in the high voltage spark. A ProMag 44 puts 44 amps into the primary side of the coil to make the 50,000 volts out of the seconday windings when the field collapses. If you had 50,000 volts at 44 amps you could run an electric chair service. I believe the spark out of a 44 is around 900 milliJoules

The reason for the tight spark gap is that the internal compustion chamber pressures get really high in a blown motor plus the mixture is just swimming in alcohol so it is really hard to have the spark jump a wide gap.

 

I would start around .018" and slowly open it up until the performance starts to drop off then close it back up to the previous good gap.