Re: 12 volt car coil for old boat motors?
It's been done on some of the older Johnnyrudes with the two-coil magneto, but it's not all that easy, and requires some ingenuity. First step is to isolate the points, because they don't work the same way they do on a car. Next, you have to have two coils, since you have two sets of points. In reality, coils designed for motorcycles that have a non-CD ignition system are fine, but car coils will work too.
No distributor is needed, since it's two sets of points and two coils. Timing on the Johnnyrude two cylinder engines is automatic and all the advance and other stuff is built right in.
The big question would be why you'd want to do that. You can replace the entire ignition system in those engines quite inexpensively, and then you can run the engine with no battery. Battery goes dead on what you want to do and you're SOL.
Some outboards have had a 12 v auto style ignition system. Those companies are out of business.
It's a far better idea to fix what's in there.
