Engines > From Plans

Upshur's twin opposed cyl. engine

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Brian Rupnow:
As work on my inline twin engine comes to an end, (and no, it isn't running yet) I've been feeling the urge to design something.  Last week I purchased the plans to "Upshur's opposed twin engine". The drawing package is really well done, and is in 2D format. One of the big pluses about this engine is that it runs a distributor cap and rotor, something I have wanted to know more about. I have redone the plans in 3D format to familiarize myself with all of the components, and it really is a sweet looking engine. I won't be selling the plans to this engine, but it should make for a very interesting build. Andrew Whale of the U.K. just happens to be building this same engine currently.  I will follow the plans for this engine---to a point. I may use a purchased set of ignition points instead of the spring brass with tungsten points soldered to it, which is used in the original plans.  Stay tuned, as after I get my inline twin engine running, this will be my next build.----Brian

Art K:
Brian,
One of the engines I brought along when I stopped in for a visit was built from the plans for Upshur's vertical single. You should have fun building this one!
Art

Brian Rupnow:
Hi Art---It's nice to hear from you. I'm building this engine "on the cheap". I have found enough material laying around in my shop to make the bottom plate, front plate, rear plate, cylinders and cylinder fins. The plans call for 0.156" machinists tooling plate for the sideplates, as they have to be silver soldered to the cylinders. I don't have any of that, but I think I have a way to substitute something else. I roughed out the plates on the bandsaw, and this afternoon I hope to machine them to finished size and put in any tapped holes and threaded holes.

Brian Rupnow:
Now, this makes me very happy!! I machined the cylinders from cold rolled steel and machined what will become the fins from aluminum, both exactly as per the plans. The interface between the cylinders and the sleeves is a "heat shrink" fit. I machined the hole in the aluminum .003" less in diameter than the outside of the steel sleeve. Then set the aluminum in my heat treat furnace for half an hour, then used my vice and a big hammer to seat the steel sleeves into the aluminum. All went well. I have been told by someone else who is building this engine that it is much better to assemble the aluminum fin section to the steel cylinder before you cut the fins. There are always "score" marks from the assembly on the aluminum sleeves (It's kind of a brutal operation) and these marks can be machined away when the fins are cut.

Brian Rupnow:
 I got up bright and early this morning and machined the fins into the aluminum on the cylinders. It went very well. A bit of butt clenching plunge cutting to 0.188" to make the fins, but lots of cutting oil and fairly low speeds got the job done.  Now I have to call and order some ball bearings and sparkplugs.

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