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Robert Best’s 1/3-scale Mogul 1 HP.

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1/3-scale Mogul 1 HP

I have two Mogul 1 HP engines on the original trucks.I am very impressed with Moguls in general, which is why I decided to make a 1/3-scale model.

I drew basic plans, and from those and the full-sized engine, I started to work.Because of the unusual shape of the engine, I decided to make wooden patterns and cast them.

I have a small foundry and can cast aluminum very well.Brass is no problem to cast, either; it just takes more heat and is more expensive.The cylinder needed to be cored and I needed the full benefit of water completely surrounding the cylinder.I also needed a solid area for the igniter that comes on the side.

I made the core pattern and cast it out of Plaster of Paris. I use the old method of making cores from fine sand and river sand, mixed with linseed oil, then baking them for one hour at 400 degrees. For the molding sand I used Petro Bond; it is an oil sand that I have had real good luck with. It is ideal for the home foundry.

Because of the way the crankcase is made, it required two patterns and two core boxes to make into one piece.I decided to make it in two halves and weld it later. Aluminum welds very well with a TIG welder and it lets me do some machine work before putting it together, such as locating the crankshaft in relation to the cam gear. The crankshaft journals were line bored for bushings after they were assembled.

The head was cast and iron valve seats were installed along with steel valve guides.A cast iron cylinder was pressed with a 1-1/8-by-1-inch bore and stroke.

Moguls are throttle-governed engines so in place of a butterfly in the head, I used a cylinder. This method is often used on small model aircraft engines and involves taking a piece of bar stock and milling a flat area that fits into the throat of the carburetor or fuel mixer. This turns like a flat piece would in large engines or small modern engines to regulate the amount of intake air.

The flywheels were cast in brass and all the fuel parts were milled or fabricated from brass.The trucks are scaled down from the original full-size trucks and I cast the wheels to match. I cast enough parts for two engines and some spare parts for mistakes, as there were plenty of them.

I worked on parts for both engines, machining where needed and fabricating parts.As I started assembling, I found where my mistakes were.The problem was for every mistake I had made, I duplicated it by making two engines. At this point, I decided to concentrate on one engine. If I was going to have to recast anything, I wanted to do it before winter set in and it was already October. Most of my casting work is done outside, and Missouri winters are cold.

I got one engine assembled and ready for testing.I used a spark plug and a buzz coil to run it the first time and it ran well.

I had made two igniters like the full-size engine, so I installed one on this engine but I could not get it to run. In the test, the igniter looked good.It was scaled down from the 1 HP andthere is not a whole lot of room for it to operate. I am not new to small igniters. I used them in 1/4- and 1/3-scale John Deeres that I made in the past and they worked very well.I installed a spark plug and ran the engine.I still hope to make the igniter work, but the engine runs very well on the spark plug.

I can't say this was an easy engine to make because of all the small parts that have to be fabricated. But, when you are all done and look back you think, "Well, that wasn't so bad."

Contact Robert Best at: 3521 N.W. 60th Terrace, Kansas City, MO 64151;