Gas Engine Magazine

The Hubbard 1912

By Staff

Haupstrasse 92 A-2492 Zillingdorf, Austria

Some time ago I fell in love with those old marine one lungers.
I started to collect information on Palmer engines, which I still
do. In the meantime, I read James Mills’ article in the January
1999 GEM about the restoration of his Hubbard. As this
engine looks very nice, I decided to build one like it and
contacted Jim. He was very helpful and made some photo sets and
also measured the complete engine for me. Scale should be 1:5 to
have it suitable for a model boat. The flywheel is 3′ 3′ in
diameter and the engine stands 57/8
tall.

Now, I started to make the models and patterns. This was not
very difficult. Very essential is to get all the nice details which
makes the original appearance. Also the small crankcase covers have
the letters ‘Hubbard’ cast in them.

I also made a corebox for all internals, water passages and
ports. The first casting was a success (it was not my first one)
and it turned out very good and accurate.

Let us have a look to the technique of the model engine:

The engine runs between 400 rpm and 1600 rpm. There is more than
enough power for a scale boat with three feet or more. This slow
runner is developed for power at low revs. Therefore, it has short
timing and low compression.

This engine can also be built easily by a novice in model engine
building. Only a small lathe is needed.

The piston is made from cast iron without rings. The steel
liner, which is supplied, has only to be machined at the outside,
to fit the casting. Plain bearings are used.

The piston water pump is driven via an excenter on the flywheel.
The pump rod extends in an original and working low tension
ignition mechanism. For good running and easy starting, a glow plug
is hidden behind the upper ignition lever. I have built good
working low tension ignitions in this size, but always the settings
of the many mechanical parts have to be very accurate.

Machining of this engine is quite easy. As it is a two stroke,
there are not many vital parts. The crankshaft is made from single
parts, which are pressed together. It is a two-piece construction,
a main crank and a follower crank, so the alignment of the
main-shaft bearings is not critical.

The brass water pump is made from tubes (supplied) which are
fitted together with Loctite.

For running this model you need not be an expert; simply connect
the glow plug, look for the carburetor setting, and run the engine.
Starting is by an easy flip on the flywheel. A small NiCad cell
with 1500 mAh lasts for approximately 40 minutes continuous
glow.

The carb works like the original and has a built-in
non-return-valve. This valve is a steel ball. Limiting its travel
adjusts the speed.

If the engine is used in a launch, a heavy base is suitable, or
also an aluminum piston can be used, which gives a little smoother
running.

So much for this engine, I think a Palmer fourstroke in the same
size will follow soon.

The casting kit contains castings, most materials and drawings
in imperial and metric. Price is $130, shipping included, cheques
accepted; finished engines $1000 (on request), available at the
address above, or fax 01143-2622-74-085,
http://www.classic-motors.at/heinz.kornmueller.

  • Published on Aug 1, 2000
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