Vertical 4 cycle engine from recycled parts

[Brian Rupnow]

You have probably all seen by now that I tried to build a "cross beam flame licker" engine and failed to get it running.  I made two different cams for it, and took advice from several well intentioned people, but it just wasn't going to run. I have spent a happy day at my computer, designing a new four cycle gas engine which will be built using almost all of the flame-licker parts without modification. Other than the sideplates and the smokestack, all of the other parts get a second chance at life. I haven't sussed out the intake and exhaust yet, but that will come tomorrow. I love a day when I can set at my computer, uninterrupted and design a new engine based mostly on parts that I already have. Will I build this engine?--Yeah, probably.  The alcohol tank will get a repositioned fuel outlet and become a gas tank.

One interesting thing about this engine is that it doesn't really have a camshaft. In order to keep everything aligned vertically and not have the con rod passing thru the camshaft, I am running a double set of gears mounted on shoulder bolts.

[Brian Rupnow]

This morning I finished up the design, and I like it. I particularly like the new cylinder head. It is almost impossible to get a 10mm thread sparkplug and two normal sized valves into a 3/4" bore cylinder head. Having the valves at an angle lets me accomplish that. I have re-used the alcohol tank as a fuel tank, with a couple of minor changes.

[Brian Rupnow]

There is a little trick in making multiple gears. If you prepare the gear blank properly, you can cut two identical gears at a time. All it means is that every time you feed the blank thru the gear cutter, you have to feed it a little farther. You end up with a gear twice as thick as one gear would be plus the thickness of your parting off tool.

[gipetto]

I would have thought that it would be a smaller learning curve to go to a stirling engine. it does look impressive. twin cam pushrod with overhead valve. I'm not aware of any commercial engines with this layout. it's like a hybrid of a T head flathead with an L head ohv.

[Brian Rupnow]

I spent yesterday and today making up gear blanks for the large timing gears, the stub-shafts which bolt to the large gears, and the two top plates. The stub shafts will have a cam cut on the end which is not bolted to the gear. There is almost a whole days work in those two top plates which are right and left hand.

[Brian Rupnow]

About 15 years ago I built the original "Rupnow Engine" and I used a complete CDI system from S & S Engineering for my ignition. The "Rupnow Engine" has been cannibalized over the years, giving up parts to build other engines, but I saved all (or most) of the CDI system. I hope to use this system on the new engine, but I had to send off an email to Roy Scholl this morning and ask him, "What am I lacking ". I think I only need a magnet and a sensor. I've been using old Chrysler points, coil, and condensers an all of my engines, but I think this new engine will be easier to adapt to the electronic ignition.

[Jasonb]

You can just make a mechanical contact and use the black and white wires that would have gone to the hall sensor. That is how I run my various S/S ignitions, Roy use dto supply a futaba socket with the two wires so it just plugged in instead of teh hall sensor wires. Only needs one to ground on the engine and the other an insulated contact.

[Brian Rupnow]

For anybody who may wonder about cutting two gears with one set-up, this is a picture of me cutting two 30 tooth gears at one time. It's a lot easier to understand once you see a picture.

[gipetto]

I think everyone understood what you meant. most of us who have made simple 2d hole arrays in a drill press have done similar by stacking two or more sheets of iron and drilling through all at once.
What i would like to see is someone cutting a skewed tooth gear. I assume it is a similar process to threading a bolt, but at a much slower rotational speed. I doubt many model makers have attempted it though, since they can use the easier alternative.
I wonder, if there is an alternative to hardening cogs for those who don't have access to ovens. could someone use a cog of mild steel meshing with a cog of brass to avoid the teeth wearing between them.

[Brian Rupnow]

Most gears in model engine world are made from plain old mild steel or from bronze. Gears of industrial machinery that see constant heavy loading may be hardened, but it would be a pretty rare thing to find on a model engine.

[Brian Rupnow]

I always feel so good when my gears are cut, and they actually mesh when installed on the correct centers. I don't make that many gear sets in a year, and although I've written all the "How to's" in a book for my reference, I still get a big pucker on until the gears are finished.

[Brian Rupnow]

Today was spent finishing a bunch of plate work and bolting everything together for a "trial  assembly".  Everything fits, and I'm quite happy with it at this stage of the game. There is going to be a lot of fussy-work in the new cylinder head. I've been in touch with Roy Scholl trying to get figured out what I need for ignition  on this engine. The old original "Rupnow Engine" from 15 years ago has been disassembled and I saved all of the electrical parts that I had originally bought from Roy when he ran S & S Engineering.

[Brian Rupnow]

I've been working away in the background. My internet has been out for 30 hours and just came back on. Somebody dug up one of the main optic fiber cables and cut it in two with a back hoe.--Bad ju-ju for somebody. My gears mesh properly. On one side they meshed perfectly--the other side required a bit of "file and curse" work, but they mesh fine now. The top plate which holds the rocker arms is dummied up into place, but I haven't tapped the cylinder for it yet.--It gets a bit complicated---I drill the holes and counterbores in the plate, Loctite it into place and let the Loctite dry, then use a transfer punch thru the holes to mark the cylinder where it has to be threaded. I've had some moments of doubt about this build, but its not costing me anything, and it's giving me something to do.

[Brian Rupnow]

Today I got some time to finish up the rocker arm support plate and drill and tap the cylinder to attach it.  Also finished and bolted on the vertical supports that the rocker arms  pivot it. I think the next parts I make will be the cylinder head and valves. I want to have them finished and in place before I do the rocker arms.

[Brian Rupnow]

Today I machined the new cylinder head. There are so many set ups required to build this cylinder head that I had to make a list of operations before I started machining it. I'm happy with the way it turned out. None of the steps were terribly difficult---it's just that there were so many of them.