The red modules are for outboards with adjustable timing while the purple ones are for motors with fixed timing. Atom made their modules color coded for different applications in all kinds of magneto equipped motors.
My ’40 Zephyr and ’60 McCulloch both have the red ones in them and it’s like night and day as far as easier starting and smoother idle compared to the points ignition are concerned. If they were still available, I think I’d change all of my motors ignition systems to the Atom modules. I still have four new ones and I think that was the last of them from Banta Saw.
I won’t even talk about the Nova II’s.
Here’s one Debe took apart.
