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.