What wire to use on 3hp McCormick Deering M Ignitor engine

[Stevie]

Hello. I have a 1918 3hp Understrike M McCormick-Deering engine. I would like to know if I use Stranded or Solid. What size. An also the Approx lenght. THANKS

[John in Maryland]

I vote stranded, stands up to vibration much better, won't break as easily.

[Stevie]

John. THANKS will go with Stranded. What size gauge do you use on those engines?

[Andrew Mackey]

Usually single strand wire was used, about 14 to 12 guage, between the mag and the ignitor. Multi strand wire allows the electricity to follow different pathways as it travels thru the wire, the resistance differential, between strands, however microscopic, allows the power to arrive at the terminal at different times, diluting the power and voltage at the points. With single strand wire, all the voltage and current arrives at the same time, giving maximum spark, when the points open. Also, with multistranded wire, humidity will corrode the strands, especially inside the covering, where it cannot be seen. Corrosion means resistance, further slowing spark. With single strand, clean the ends, remove the issue!
Andrew