Reader’s Scale Engines

By Staff
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Features automatic intake and exhaust valves. John's most recent project is this freelance hit-and-miss.
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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’

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

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

I also recently finished a scratch-built 2-inch-by-3-l/2-inch
freelance hit-and-miss.

Gas Engine Magazine
Gas Engine Magazine
Preserving the History of Internal Combustion Engines