Above: right side view
Below: left side view
ENGINE NO. FOUR DATA
Type: Vertical Hit & Miss
Displacement: 1.20 cu. in.
Compression Ratio: 6:1
Ignition: originally coil/spark plug; later glow
Fuel: 15% nitromethane/methanol mix
Max. RPM: 6,500 (3,500 governed)
Est. Horsepower: 0.45
Background -- After building
my first Hit & Miss engine from a kit I became more intrigued
by this old type engine, originally built by the Perkins Co.
The result is this vertical Hit & Miss engine
with a flyball governor.
Construction -- I sent for
drawings for a quarter scale model of this engine, but after
looking them over decided I would make my own design. For one
thing, the quarter scale made a model that was too large for
my taste. I also didn’t
care for some of the design features from Perkins. I used a
conventional rocker arm to operate the exhaust valve and an
atmospheric (automatic) intake valve. A vertical shaft was
run at 1/2 speed off the crankshaft which carried the ball
This was the last engine for which I made patterns
and castings. Since that time I’ve stuck to billet machined
type of parts. I have a Bridgeport type mill which can handle
any small engine parts.
Operation -- The ball governor actuates a lever
which blocks the exhaust valve when the speed gets beyond a
set value. The engine then slows down until the lever backs
out and the engine resumes speed. This system
worked quite well.
Detail of flyball governor
ENGINE DETAIL PAGE LINKS
(click on buttons)