I was talking with a friend at the field the other day and it
got me thinking about how are gas engines ignitions are wired....

Can someone explain why the negative wire for the spark plug
is run directly to the plug instead of a simple ground wire screwed
to the block of the engine?

As it stands now we only have a pressure fit around the spark plug
for the negative side of the ignition, I would think a separate wire
bolted to the frame would be a more reliable setup. I also would think
that a single wire (the positive wire) running to the spark plug we could
have a nut or screw to secure that wire wire to the spark plug. That
make room for a very nice shield boot to slip over the plug, and room
for a much heavier shielding on the single positive wire.

Thanks for your help.