I'm restarting my past effort to get a single-cylinder engine to run purely on Hydrogen fuel. I'm starting from scratch with an old 6.75HP lawnmower engine (the engine runs beautifully). I'll be building a testing rig around the engine, modifying the engine to run stand-alone (removing the rotational inertia of the mower blades causes the engine to run differently), ripping out the old ignition system and replacing it with a brand-new microprocessor-controlled electronic ignition system, adding fuel injection for the Hydrogen, and ultimately using the engine as a test bed for collecting data and a proof-of-concept for future projects.
Here I've ripped the cover and pull-start off of the engine.
This is the magneto-driven ignition system that is currently on the engine. To adjust the ignition timing, I could try and re-position the pickup coil perfectly in the new position, but that would be way more trouble than it's worth. It's far easier in this case to add an electronic system, which will allow me to adjust the timing on the fly, extrapolate data about the current RPM of the engine, power curves, etc.
Here you can see I removed the engine from the lawnmower. The carburetor will eventually be completely replaced by a gas-metering system to precisely inject Hydrogen gas into the system.