Sandhurst Engine: A Progressive Project

By Staff
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3980 Becket Drive Colorado Springs, CO. 80906

I started my model engine building hobby in the early 1970s
making bar stock steam and Stirling engines of my own design,
followed by machining Stuart-Turner steam engine casting kits. In
the late 1980s I also got into machining gas engine casting kits,
and have built a number of them, several of which were featured on
the back cover of the January 1997 issue of GEM.

I had a ‘1978 Craft man ship Catalog’ from Caldwell
Industries of Luling, Texas. They were primarily in the business of
selling steam and gas engine casting kits. I greatly admired a
particular scale model beam type steam engine but just never got
around to placing an order for it. Years passed and when I finally
decided to go ahead and order the kit I found out that Caldwell
Industries were no longer in business!

More years passed but I just couldn’t forget about that beam
engine casting kit. When you know there is something you can’t
have, you just want it even more! Finally, in 1995 I placed a
classified ad in a hobby magazine to see if someone might have that
unmachined casting kit that I could purchase. In due time I got a
phone call from a fellow in Wimberley, Texas, who had the steam
engine kit. After working out a sale agreement on that, he asked me
what else I might be interested in, so I asked what else he had to
sell. He related that he had bought much (maybe it was all) of the
remaining Caldwell inventory after they went out of business. Among
other items he had for sale, he mentioned a ‘Sandhurst’ gas
engine casting kit by Stuart-Turner. I remembered seeing that
engine in the Caldwell catalog of 1978. I was told that the
castings were pretty rusty because the inventory he purchased had
been in storage for years in a barn with a leaky roof. After much
negotiating, we arrived at a sale price for that kit also.

After I agreed to buy the Sandhurst kit he informed me that he
originally had two kits and had sold the first one to a fellow in
Houston, Texas, who worked for an oil company and traveled the
world over. On a trip to England the fellow visited Stuart-Turner
to buy a certain engine kit. He mentioned to them that he lived in
the U.S. and had a Sandhurst engine. Upon hearing that, they
informed the fellow that the Sandhurst kit had long ago been
discontinued and after checking their records, also informed him
that they had only shipped two Sandhurst kits to the U.S.! The
castings soon arrived and indeed they were awfully rusty so I took
them to a cemetery monument establishment and had them sandblasted.
As soon as I got them home I gave them a coat of primer so they
wouldn’t start to rust again. Looking over the drawings I
discovered that they were dated 1933!

The engine is not a model, but was intended by Stuart-Turner to
be a real working engine for various light duty jobs. The bore is
2′ with a stroke of 3′. A platform casting was provided to
mount and include magneto for ignition. The magneto was to be
driven from the camshaft. My standard ignition system is a simple
transistor ignition circuit and old style Briggs & Stratton
magneto coils powered with a 6-volt battery which works very well
indeed. I decided that a better use for the platform was for
mounting a radiator and water pump for cooling so I made a brass
radiator, fan and centrifugal pump to circulate the cooling water.
The water pump/fan is powered from the cam gear using a geared jack
shaft and an ‘O’ ring belt. The pump/fan runs at five times
the crankshaft speed.

The logical place for the fuel tank was between the truck frames
and below the carburetor, so there was a need to pump the fuel up
to the carburetor level. Not wanting the complexity of a mechanical
fuel pump, I designed and built a diaphragm pumping carburetor
similar to those used on weed eaters, etc. The diaphragm was sized
to pump more fuel than the engine needs and the excess fuel drains
back into the fuel tank.

A small DC generator is mounted just to the rear of the radiator
and is belt-driven from the crankshaft. The 6-volt ignition battery
is used only for starting. Once the engine is running, a switch is
thrown and ignition is then powered by the generator. The ignition
coil, battery and ignition circuit are all in the battery box. I
use a magnetic hall effect sensor instead of a point set for
ignition timing. It is mounted on the flywheel side of the camshaft
and also allows for ignition advance and retard.

I designed and machined a rather whimsical polished brass ball
muffler, and the oak truck design is a ‘barnyard mixture’
of ideas that I gleaned from American Gasoline Engines Since
1872
by C. H. Wendel. A curious stroke of luck was that on a
whim I bought the cast iron curved spoke truck wheels at the
Portland, Indiana show several years before I even had the engine
kit. They are a perfect match to the engine flywheel.

I have read many of the ‘once-in-a-lifetime’ engine find
stories in GEM over the years and thought that kind of thing would
never happen to me. I am completely satisfied to have one of the
two known Sandhurst engines in the USA!

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