More ACME/S.M. Jones Engine Information

By Staff
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Courtesy of Gas Engine Magazine Staff
A factory photograph of a 10hp ACME equipped with a “Scholl” pattern clutch and gear reduction

I read with much interest the article on the ACME/S.M. Jones gas engines. There are several of these engines running. These are 10hp geared units and are used to pump wells, generally two wells at a time.

Photo 1: Valve location. The red tag is on the unusual third valve

These 10hp engines are 601 cubic inches in displacement. I have made head gaskets and have measured the cylinder diameter and length of the stroke. These engines are very durable, as some that we operate are close to 100 years old. They will run in either direction on account of the unusual valve setup. However, if they are run backwards, they tend to loosen the bolts that hold the clutch shaft to the flywheel and can break off these bolts.

Photo 2: Rear view of engine, cylinder, crankshaft, and bull gear

I took several pictures of a very dirty engine, now out of service. Photo 1 shows the valve location. The red tag is on the unusual third valve. The stem is inside the round projection. Photo 2 shows a rear view of the engine, the cylinder, the crankshaft, and the massive bull gear. Photo 3 shows the “Scholl” pattern clutch. The inside hand-wheel is tightened while the outside wheel is held steady. Photo 4 shows the disc crank and wrist pin.

An ACME is a rather slow running engine, and with the gear reduction, the final disc crank turns about 14-16rpm. The rods fastened to the wrist pin are connected to a well, one on each side. As a result, these units were located in a direct line between wells where possible. I ran this engine as a young man. I was about 14 or 15 years old at the time, and the engine was old back then. There is no brass tag on this engine, only a three-digit number stamped on a raised boss on top of the bedplate, just behind the cylinder oiler. The owner’s manual says the weight of a 10hp geared unit is 4,500 pounds.

If anyone has a similar unit and needs help or information, feel free to contact me. And please overlook the typing errors. At 84 years old, I ain’t quite what I used to be …

Best regards,
Harold R. Keller
9322 State Route 13 SE
Glouster, OH 45732
(740) 347-4706

Harold, at 84, you sound sharper than most at 50. And any typing errors you made, you corrected with pencil and pen before mailing it out. This is one of the more intriguing letters we’ve received in years. To learn there are yet a few ACME engines running (and perhaps even still pumping?) is incredible. We sent you a letter hoping to learn more, Harold, and we’re hoping to share more of your ACME engines with GEM readers.

Photo 3: The

Readers: Harold’s letter inspired us to launch a new award for the best engine story we receive in an issue. For sending his letter, Harold gets to pick any single book he wants from the Gas Engine Magazine Bookshelf or a Gas Engine Magazine T-shirt. Moving forward, if we pick your letter, you’ll get the same offer. Mail or email them to my attention at the address at the bottom of this page. And thanks again, Harold, we’re looking forward to learning more.

Photo 4: The disc crank and wrist pin

Please send your questions and comments for Flywheel Forum to Gas Engine Magazine, 1503 SW 42nd St., Topeka, KS 66609-1265 or email

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