Scale-Model Gas Engine Building

A California gas engine model maker's scale experiences

Olds Model

Olds: Paul Breisch castings.

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Back in the late 1980s, I attended my first gas engine show. I have collected and worked on old machinery all my adult life, and that first show was a dream come true - there was so much great stuff. It was at this first show that I saw a model and talked to the gentleman who built it. I showed the model to my wife and said, "I think I could build that." She responded, "You need a hobby, so go for it."

The years have passed with lots of chips on the floor and correspondence with model builders and interested people. What follows is an account of my models and my impressions of building them:

This was my first model. I was able to machine all the castings with little difficulty. However, when it came to the valves, gears, springs, governor, etc., I did a lot of head scratching with many phone calls to Homer Stevens, who walked me through all the spots where there is no substitute for experience - most notably building a one-piece crank, seating valves and setting exhaust valve timing. When the Olds first ran, I called Homer so he could hear it, and he knew I was hooked! The Olds model would be very good for anyone interested in building their first. In retrospect, I was lucky it was my first as I have built a few since that may have discouraged me.

Homer then sent me a set of castings for a Fuller & Johnson he had, saying he didn't think he would get to it due to his age. I built it, called him up and let him hear it run.

Domestic sideshaft
This is one very interesting model, with its sideshaft and all the action going on at the head. This model is a challenge to build, and the cylinder casting is very unique. When I finished it, I wrote an article for Gas Engine Magazine about my experience.

As I waited for my copy of GEM to arrive, I received an overnight express delivery letter from New York, but I had no idea who the sender was. I read the letter and had to laugh - although my copy of GEM hadn't arrived, it was clear my article had been printed. The sender had built the Domestic, but couldn't get it to run. He said, 'Call me collect ASAP. I'm a machinist of 60 years, getting old and don't want to waste time. Thanks.' I called him (not collect), and we got it all figured out and running in just a few calls. He told me his nephew lived about 30 miles from me. I knew the name but never met the nephew, Francis Ford Coppola. Small world this model interest brings along.

Fairbanks-Morse Type N
This is a very quiet-running engine. The castings are high quality, and the model is easy to build. The governor weights in the flywheel show nicely when running. At the 1993 national EDGE&TA show in Grass Valley, Calif., there was a 25 HP Fairbanks N. I put my model along side the real thing, making it clear to people unfamiliar with the hobby what the term 'model' means. This model has spent a lot of years in my living room, and it's my wife's favorite.

This is an interesting model to build. There are lots of castings, both cast iron and brass. With its heavy flywheels, it can run fairly slow. The governor stays hooked up so long the water in the hopper never gets hot! The castings for the brass muffler are an especially nice touch. In fact, I took the muffler off the other day to see how it would look on the gearless Olds I am currently building. The Olds has a very similar design but is made out of cast iron. Looks like I'll be calling Richard Shelly for another set of muffler castings.

The Gray is a straightforward model to build. This model likes to be belted up to a load and runs strong. With close to a 2-inch bore, is has plenty of 'bark' to it. The brass castings for the timing lever and associated parts are real nice.

This model was my first crosshead design two-stroke. The machining and assembly were straightforward enough: My problem was getting it to run in one direction without slowing down and reversing, especially when cold. It seems that when it compressed the charge on the backstroke and then went forward for the power stroke, the compression on both sides of the piston was about equal. Proper hot-tube timing is important on this model.

Fuller & Johnson
This is one strong runner. With a 2-inch bore and a 2-1/4-inch-plus stroke, it definitely needs to be bolted down! The castings are a little rough, but there is plenty of material with which to work. However, I could not make sense of the governor assembly, as I had never seen one like it before. Ed Chick mailed me one made out of aluminum, a third larger than scale, so I could see how it worked. That helped a lot. Yes, I did mail it back. It wouldn't fit on the model - I think Ed had that in mind!

I built the left-hand model first. This was model building at a new level for me as I had no idea how the engine could run at such a small scale. Brad Smith from Franklin, Wis., helped me a lot in building this model. He had 'been there, done that,' and mailed me his notes and recommendations on how to build and run the Reid. I made the hot tube using a design by Norman Colby from Claysville, Pa. It worked fine.

Brad wrote a series of articles in 1994-1995 for Modeltec magazine describing every detail on building the Reid model. I enjoyed the series so much I called John Burns one evening and asked him to send me a right-hand model. He told me I was a glutton for punishment.

The Reids get a lot of attention at shows on the West Coast, as there aren't many of them out there.

A classic show story I will never forget was at the Western Regional EDGE&TA show in San Jose, Calif. The Reid was running when a lady in her 40s, dressed to the nines (definitely a 'city' woman), asked me, 'What is that?' I took a cigarette from my packet, bent over the side of the hot tube, lit the smoke, took a puff, looked her square on and said, 'It's the world's most expensive lighter.' Her response, with a big smile was, 'I love it!'

Scratch-built Vertical
In the mid-1980s, Debolt Machine made a casting kit for a vertical Perkins, but I was never able to find a set of these castings. Always wanting a vertical model, I bought a pair of Galloway fly wheels from Richard Shelly and built this model from scratch.

The crank base is machined from a 6-inch cube of solid 6061 aluminum. The cylinder is from 4-inch 6061 stock, and I put a cast iron sleeve in the bore. The head is brass. Rather than install bushings on the crank, I put a pair of roller bearings in the housing. It does run 'free.'

I've told my wife over the years that we need to own one 'real' engine. Even modelers should have at least one. Just visible behind the window is our 30 HP Type S Foos. That is another article for Gas Engine Magazine.

Gearless Olds
Last summer, Debolt Machine sent me some information on a vertical they had cast. This has been a busy year out in the shop, and I still have the carburetor and plumbing to do, as well as build a base and get it to run. Machining the castings, building the crank, rod, etc., has been straightforward. The timing assembly and the governor are so different, I watched a video that came with the kit so I could understand how it all works. I have never had a video come with a model before, but it has really helped. I like the Galloway muffler on it.

Process Points
I make the crankshaft assemblies in one piece, and while that takes extra time, they come out true. Some of the four-stroke models call for igniters, but I have had little luck building a scaled-down version of this part. They are so small and delicate the parts seem to last nowhere near as long as the other pieces of the engine. It is frustrating to spend hundreds of hours building a model then trying to fuss with the igniter. A 10-mm spark plug and buzz coil is easy and pretty fool-proof. I have seen a lot of models run on igniters, and my hat goes off to the builders who can pull that off. Maybe after I retire I'll have more time and patience to play with igniters.

If I can offer advice to anyone interested in building a model, it would be to talk to the people who cast or sell scale engines and ask for names of other people you can talk to who have built that particular model.

I think it is very important to have the bore honed by a shop with an industrial cylinder-honing machine, not a hone put in a drill motor. Exhaust valve timing is also important. Make sure the valve is open at least by top-dead-center on the exhaust stroke, so the exhaust is completely removed, and the cylinder is clear for a fresh charge. The engine will also run cooler. I run all my models on propane.

When running a two-stroke engine, NEVER look directly into the hot tube! Use a mirror to check the flame. As silly as it sounds, there are people out there who see a model running and think it is a toy. Beware: This little 'toy' can burst your fingers faster than you can blink!

One last piece of advice, measure twice, cut once. Enjoy your hobby.