Looking for a Project? Don't Trash That Old Compressor!

Crafting an Inverted Engine From an Old Compressor is the Perfect Winter Project

| January 2005


'Above: The compressor engine as it sits on its custom, owner-fabbed cart. '

This engine started life as a small Sears compressor I used in my garage for many years, mainly to air up tires. It picked up a leak in the tank from rust, so I was going to junk it. Then I thought of making another compressor engine [see Robert's other article, "Compressor Engine," on page 5 of the February 2004 issue - Editor]. To be different, this time I would make an inverted engine using the same governor, fuel and ignition mechanics as the Au-To Air.

Inverted Issues

After building this engine, I can see why inverted engines are few and far between. On this engine the base and exhaust valve bracket are both attached to the head. This makes it difficult to time and make valve adjustments. Also, if the engine sits for any length of time, oil seeps into the combustion chamber and fouls out the spark plug.

One thing about fabricating your own engine is the field is wide open for your own design. The paint - and lots of spit and polish - can separate a home-built engine from a manufactured engine or a "look-alike" model.

As you can see, the lion heads and legs on the trucks are very unusual. I carved the patterns in wood and cast them in aluminum in my home foundry.

This is a hit-and-miss engine with heavy, 8-inch diameter flywheels. It has a 2-1/4-inch bore with a 2-inch stroke. The one end of the crankshaft did not extend through the housing, so I added 5 inches to that end of the crankshaft. I made the round part of the base from the cylinder sleeve of a 3 HP International M, and I got the valves from a small Clinton engine. The flywheels are brass and were cast by a fellow member of the Mo-Kan Antique Power Assn. of Kansas City, Mo. Engine speed can be controlled by a collar and setscrew that can be moved up and down just below the flyweight governor. The fuel tank is enclosed inside the base.

As manufactured engines are getting more expensive to collect, and rusty iron harder to find, a compressor engine may be the perfect alternative to stay busy when cold weather sets in.