Originally Posted by dirtybird

That is caused by poor insulation in the unit.
The old C&H units I had would make a spark all the way from the electrode to the cap if the spark plug was out. At least 1/2 inch. The insulation in those units was so good thye spark simply had no other place to go.

BTW I should add not to do the finger test if you have a carbon fiber prop.. You dont want that charge to go near your heart