Sandhurst Engine: A Progressive Project


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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!