Gentlemen,
A number of years ago a fellow who goes by the name of Put Put Man on one of the modeling forums completed a build of a tiny hit and miss engine based on a horizontal water cooled type. It has a bore and stroke of .375 x .50 and is made primarily from aluminum. The piston is a honed fit to the cylinder and uses no rings or O rings. The original design, although based on a hit and miss engine, didn't hit and miss but rather ran to whatever the carburetor would allow (quite fast). Later another fellow (Gail) would incorporate his own design for an effective hit and miss mechanism.
The drawings were published and quite a few of them were built. I built one of the first designs and then later added a more conventional hit and miss mechanism. My next version was almost identical to the first with the exception that I made it with an air cooled cylinder. I then published the changes for that design. My next example was to start with the original design and dimensions and transform it into a water cooled vertical type.
Although these little engines can run pretty warm due to the high speed, with the lockout hit and miss mechanism they will run all day and barely get warm to the touch.
My vertical is made mostly from aluminum and uses an aluminum cylinder jacket with an iron liner. The crankshaft is made in one piece from 1144 steel. The gears are home made. The original design had the base of the engine as the fuel tank. This version being vertical required a tank that was close to the centerline of the carb to facilitate fuel flow so I made up a tank and mounting arrangement for it.
The engine uses a Hall transistor trigger for the electronic ignition and is timed about 5 degrees BTDC. I changed the head design to use a home-made 8-36 spark plug.
I am posting some of the photos of the engine here and will post a video in that section of the forum.
gbritnell