Modeler’s Corner

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Tom Jamboretz’s model hit-and-miss engine.

Bar and flat stock hit-and-miss

I have been collecting old engines for about six years and am a
member of the Illinois-Missouri Tractor and Engine Club in the St.
Louis area. The more gas engine shows I attended, the more I knew I
wanted to make a model hit-and-miss engine. Most of the choices I
found were casting kits made by many different people from all over
the United States and the United Kingdom.

I finally ran across a hit-and-miss engine that was made using
bar and flat stock. It has a 1-1/8-by-1-1/2-inch bore and stroke
and no castings. This was a big advantage to me, as I did not have
a milling machine at the time. All I had was a small lathe and a
drill press. The engine was designed and drawn by Harold Depenbusch
in Kansas, and came with instructions, drawings and a parts list.
There were a few parts I purchased, such as gears and a miniature
spark plug.

I started with the base, which is made from 3/16-inch sheet
plate and heli-arc welded together. To this I added the iron
cylinder and surrounding water hopper. These I tack-welded and
sealed with JB Weld for a watertight hopper.

The head is made of aluminum with the 7/16-inch valves of
stainless steel. The valve seats are actually cut in the aluminum
head with mild steel guides and then lapped to give a good seal.
The piston and rod are also aluminum with two cast iron rings from
Otto Engine Works.

The biggest challenge to me, the non-machinist, was the
one-piece crankshaft. It is made from a piece of
5/8-by-2-3/8-by-8-5/16-inch flat cold-rolled steel. After laying
out the centers and sawing away excess metal, it went onto the
lathe to machine the throw. I had to make a long reach cut-off-type
tool to reach the throw. It worked surprisingly well.

After making the rest of the parts and reassembling, I had a
hard time getting the model to run the way I wanted. However, it
came around after a long thought process and help from a friend in
Oregon. It turned out the exhaust camshaft was made wrong, so I
needed to cut a new one to bring the exhaust valve timing to the
correct position. I did deviate from the plans on occasion, such as
changing it to run on propane (which required a demand regulator to
be made) and putting the ignition point on the other side of the

I painted it a very bright yellow and made the base from a piece
of white oak to give it some weight. I am very pleased with the
results and take it to shows where other engine enthusiasts can see
it running, hitting and missing.

Plans are available from Harold Depenbusch at (620)

Contact Tom Jamboretz at: 416 Larkhill Court, Webster Groves, MO
63119; (314) 962-3493;

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