Re: Johnson AD-12 mystery

[frankr]

So, you are sure the flywheel is hitting the armature plate, and not the coil? Possibilities of that are pretty few, and the key is not one of them.

Are the armature plate mounting rings assembled correctly? The aluminum ring that goes under the brass ring must be installed flat side up, not tapered side up.

Does the armature plate flop around? In other words, is it broken or badly worn at the center?

The flywheel may be bent from somebody removing it with a puller that grabs the outside rim. Not necessarily you but possibly by somebody in the past. If it is, you need a replacement flywheel.

Since you mentioned the key, I am wondering if the keyway in the shaft or flywheel is battered? That happens from failing to install the flywheel correctly, and destroys the parts. Both tapers must be clean and dry and you must use a torque wrench to tighten the nut to 40-45 foot pounds. Battered keyways affect the magnet and points timing relationship. But not just one set.

The #1 cause of no spark is dirty or mis-adjusted points (assuming parts are all good)