A couple of years ago I purchased a 3 HP Fairbanks-Morse Z from another collector. The engine was restored years earlier, so there really wasn't any work to be done on the engine. The mag was missing, along with the crank handle, and the crankshaft shield. The engine is serial #574063, built in 1924, and is throttle governed.
A few months later I was telling a friend about the engine. He related that he had a 3 HP Fairbanks-Morse Z that he would sell, so I went to look at his engine. I was somewhat disappointed to find that it too was missing the magneto, but it did have a hand crank and a crankshaft shield. I thought he was asking too much money, but as most of you know, when an antique gas engine is offered for sale most engine nuts lose all sense of value and common sense. So I bought it.
When I was unloading the second engine, I noticed it seemed to be a little different than my 3 HP throttling governor Z. After further investigation in Power in the Past Volume 2 and Encyclopedia of American Gasoline Engines, both by C.H. Wendel, I discovered that Fairbanks-Morse built a cheaper engine to compete with International Harvester and other companies who were building low cost farm engines.
The Fairbanks-Morse Z economy model is hit-and-miss governed. It has a battery box which was originally equipped with a Model T Ford buzz coil. The carburetor has no needle valve – it has a fixed jet, and the fuel mixture is controlled by opening or closing the air shutter. The dripper is all metal, and has no glass on it anywhere. The governor holds the exhaust valve open and also interrupts the spark (which saves the battery) when reducing engine speed. The governor has a speed adjusting lever so the engine speed can be changed very easily. When I disassembled the engine I found out that it was originally red. I have read that the 1-1/2 HP model had disc flywheels but this one had spoke flywheels. The serial number is 571451, built in 1923.
I soaked the piston for three months with penetrating oil, then gently tried to get it to move. For three days I tried everything to unstick the piston. Finally, in desperation, I built a fire in the hopper until it was hot; then I laid a steel plate on top of the piston and beat on it with a 16 lb. sledge hammer. After 45 minutes of beating on it, the piston began to move. To my surprise, all of this abuse did no damage to anything. I would not recommend this method to anyone because of the possible damage to the piston or engine block.
The battery box and the fuel tank were badly damaged so I had to hand-make these parts.
I had some trouble with the spark interrupting mechanism because it wanted to short out all the time, but I finally got it restored to perfect working order.
I have never seen a 3 HP hit-and-miss Z like mine, so it must be somewhat uncommon. I bought this engine for parts, but since it was unique, I restored it. Maybe I didn't pay too much after all. Sometimes losing all sense of value turns up a diamond in the rough.