Back in July of this year I completed a Silver angel engine as designed by the late Bob Shores of Florida. It is not a scale model of any particular prototype, but a rather interesting design in itself.
It was an interesting project to build and not all that difficult as models go. All machined from solid stock, except for the flywheel which is a casting.
During the process a demand regulator was constructed so it could be run on propane rather than gasoline.
I even built my own spark plugs to use in it.
Finally it was completed. It did not have much compression. Cranking it with an electric drill, it would pop a little, but simply would not keep running by it's self. Disappointed, I set it aside for a while and built several other projects. But I was bothered by the fact that it had little compression and would not run. I assumed the valves were leaking, so a few days ago I took it apart and re lapped the valves with a polishing compound. Still no compression. But when I removed the spark plug and put a finger over the hole, lots of compression. A little more investigation revealed that the packing nut holding the insulator in was hardly finger tight. After getting that sealed up tight, it runs like--- well an old hit and miss engine ought to run. Take a look at the video and see for yourself.