Reader's Scale Engines

| April/May 2004

  • Freelance hit-and-miss.
    Features automatic intake and exhaust valves. John's most recent project is this freelance hit-and-miss.
  • John Bold's 'Loyal Cycle'
    John Bold's 'Loyal Cycle'

  • Freelance hit-and-miss.
  • John Bold's 'Loyal Cycle'

2681 Brooks Court Turlock, CA 95382

The November/December 1972 issue of Gas Engine Magazine featured an article by Arthur Stone of Elfers, Fla., about an engine he built and referred to as a 'Loyal Cycle' engine.

The engine had automatic intake and exhaust valves - no gears or cams. The exhaust valve is located about halfway down the stroke so that the remaining travel of the stroke draws in the fresh gasses to be compressed for the next power stroke.

After seeing this article, I built a somewhat crude model and, by golly, it ran. Since my main hobby during this time was building steam engines and steamboats, this project was stuck under the bench for the next 30 years. When I began building model gas engines I tried to resurrect the earlier model but decided to start over and do a better job.

The new model has a 1-1/4-inch bore and a 4-inch stroke. It has a cast iron cylinder and aluminum head. It runs on either gasoline or propane, and it sounds like a four-stroke when running free but when a load is applied it changes to a two-stroke sound. Arthur Stone said he used an engine of this size and type to run his lathe.

With all the interest in building model gas engines, I'm sure there would be some interest in this concept.