This is an Eisemann aircraft magneto pictured but tractors often used an impulse coupling as well. It catches as the magneto is turned slowly and winds up a spring in the drive to flip the magneto quickly to give a good hot, late spark for starting.
This is a 14 cylinder ignition system being tested on original WW2 test equipment after repair from a large radial engine, like what you'd find on a DC-3, PBY Catalina, or B-24, etc.
At one point, building mine, I had two model A engines, and I called 'Sam' to ask him what he thought about that engine over an A65...he said: "It depends on how much you like forced landings!"
The airplane was built by Bob McKinley near Louisville, KY. He flew it for about 10 years and then past away a few years ago, and I purchased it from his estate. He did a fantastic job, far better than I could ever do. I filmed this video mainly to watch my wheels during landing, I had a feeling my tailwheel spring was a little too light, which it looks like it was. I have since added another partial leaf and its stiffened up a bit.
