Bigger is not always better: Just ask small engine enthusiasts. Where to find them? Go to a show where engines are surrounded by smoke, steam and loud noises ... but you won't find them there. Look for the smooth-running miniatures on a tabletop nearby.
Mini engines, usually less than a foot long, are built to exacting scale, proportions and detail. Some are replicas of real antique engines, while others are hybrids conceived by their hobbyist makers.
Bill Gorman, a mini engine maker, can often be found with his creations at shows in the region around his Independence, Mo., home. An expert on heavy equipment engines, he shifted into minis in 1979 and continues to craft and show them in retirement.
Among his favorite shows is one at Republic, Mo., near Springfield. He's found that being a member of the MO-KAN Antique Power Association there has been rewarding, both in participating in shows, and discussing minis with other craftsmen.
"After I retired, I thought I never wanted to see the inside of another engine," Bill says. "But I guess that it gets into your blood, so now mini engines it is."
"I first built two little steam engines, drawing on printed information, such as the Lindsay publications, old engineering plans, books and magazines. I look toward building engines and things with the old principles that did work."
Bill typically scales down and makes his own miniature plans, drawing on his drafting and metallurgy skills. One method he uses is to settle on an engine bore size, then scale down the rest of the engine around it.
A beautiful antique W-111 replica engine Bill built is based on one in the John Deere Model D, built from 1923-53. Horsepower of the large motor was increased substantially over the years, and it was considered very tough and reliable.
The JD W-111 mini engine is 1/8 scale and has a 1-1/8-inch bore, a 1-3/8-inch stroke, and valves with 3/8-inch outside diameter. All gear ratios are the same as the JD, with the fan running four times crankshaft speed.
The mini engine has splash lubrication, with the overhead assembly lubed by a line from the timing case. The radiator has 32 1/8-inch brass tubes running vertically between headers.
Another of Bill's creations is a mini Loyal engine, a French design from 1871.
"It's unique, as it's a two-cycle," he says "but it has no transfer case pressure and does all cycles above the pistons."
The Loyal has a 1-1/8-inch bore and a 2-5/8-inch stroke. This engine has a typical poppet valve in the head for intake, plus an exhaust valve at mid-stroke. This valve has a reversed seat and is closed by a spring pushing on the valve stem. As the exhaust port opens, the valve opens to let out pressure. The spring then closes it, and on the second half of the down stroke, the vacuum opens the intake valve to let in fuel and air. Then up on compression, and "boom."
Bill also made a mini based on the Atkinson engine, designed to circumvent the Otto patent type which was the first four-cycle compression engine.
Atkinson used a toggle linkage, so all four cycles happen in one revolution instead of two. That produces twice the power from the same displacement and runs more smoothly, Bill explains.
Atkinson put lobes on the crankshaft so it runs the same as engine speed. It fires twice as often, so it makes a good generator engine with the cycle-current rate steadier than with the Otto design.
Bill also built a hit-and-miss mini engine likely more familiar to small engine fans. It's not a scale model, but runs like most of the larger ones. It's a push rod engine with a 1-1/6-inch bore and 2-inch stroke. This engine was built from a Lindsay plan with modifications. The cylinder block, for instance, was machined from a block of aluminum instead of being brazed from many parts.
Bill is now at work building a Smalley-design mini based on a 1920s-30s marine engine. The mini will be air-cooled, rather than water-cooled, as the Smalley was. He is planning to use the engine in a small vehicle to ride around in at shows.
"I really enjoy the mini engine hobby, both building and showing them," Bill says. "I just love it, and have made a lot of friends in the process." FC
For more information: Bill Gorman, 3609 Brentwood, Independence, MO, 64055; (816) 478-0613.
Gary Van Hoozer is a Missouri writer specializing in vintage agriculture and farm history.