Oscillating I.C. Engine

[Brian Rupnow]

EXCELLENT NEWS!!! Engine starts and runs, but medium strength spring is still a bit too light. Engine is new, and still a bit stiff, so it dies before it can go from "miss" mode back into "hit" mode consistently. I am now changing up to strongest spring, but things are really looking positive!!!

 

[Gerhardvienna]

Gerhard---the weak spring is on the governor, not the valve.---Brian

SORRY___My mistake:wall::hDe:
Good to hear it`s running, congrats!
Regards
Gerhard (waiting for some moving pics;D)

 

[Mechanicboy]

Excellent done! The next engine will be double acting oscillating engine?

 

[Brian Rupnow]

No joy yet. The strongest spring does work all right (near as I can tell.) I had the engine running for short duration blasts, and grabbed the video camera a dozen different times but the engine wouldn't oblige me by staying running. I played with the ignition timing, first advancing it, then retarding it, looking for the "sweet spot" but never found it. I adjusted the carburetor needle to every conceivable position, but the best run I got was only about a two minute duration, with the engine gradually slowing down and coming to a stop. After about 50 different attempts to start the engine, I was rewarded with a rather ominous "clanking" sound every time it started. Nothing was visibly wrong that could be seen from outside the engine (and almost everything is on the outside of the engine.) The compression has improved exponentially, so the pressure caused by the engine firing has firmly seated the valves. I never reached the point where the engine "took off" and gained rpm until the centrifugal governor was activated, but I was able to activate it by spinning the engine fast enough with my 3/8" variable speed drill, so I know the centrifugal governor is working. I will pull the head off the engine sometime today and make sure that the piston isn't coming adrift from the connecting rod, and ascertain that my pressed together crankshaft hasn't slipped out of alignment.

 

[Brian Rupnow]

TA-DA
[ame]https://www.youtube.com/watch?v=_j7U56CSLtI&feature=youtu.be[/ame]

 

[Brian Rupnow]

I pulled the head off to check the piston, to make sure it hadn't come loose from the con rod but it was okay. I then seen that the set screws holding the flywheel and key in place had come loose, and that was what was making the nasty "clank" sound at the end of yesterday. I tightened them up and then I monkeyed with the ignition timing and fuel mixture some more. I advanced the spark more than I had tried yesterday, and I believe that is what finally did the trick. Now I have to try and suss out why it is not revving up. The flywheel is heavy, but that won't keep an engine from revving up. A heavy flywheel will only keep an engine from revving up quickly. I have noticed that the intake valve doesn't seem to be moving at all, although it must be moving some for the engine to run at all. I may try cutting half a coil from the inlet valve spring to see if that makes a difference.

 

[Brian Rupnow]

Here we are going in and out of hit and miss mode. As I suspected, the spring on the atmospheric intake valve was too strong, making it difficult for the engine to draw in enough air (and consequently fuel) on the intake stroke. I removed the spring and cut off one full coil, and the engine immediately reached into a much higher rpm range with no other tweaking. The new higher rpm range allows the engine to go in and out of hit and miss mode, but it is running much too fast. I will now put the "medium" governor spring in place and see how much it slows the engine down.
[ame]https://www.youtube.com/watch?v=qymo4QU9d0Q[/ame]

 

[Brian Rupnow]

We're done!!! This is the correct speed for a hit and miss engine to run at. Thank you to all who have followed this thread, and I truly do hope that any new-bees following may have learned something new.----Brian
[ame]https://www.youtube.com/watch?v=4Q1dWMnXfj0&feature=youtu.be[/ame]

 

[jimjam66]

That oscillating cylinder is SO weird to watch! Fantastic work, the only question now is: WHAT NEXT?

 

[gbritnell]

Very well done Brian!
gbritnell

 

[Gerhardvienna]

Great engine! This is a real good runner, gratulations!
Regards
Gerhard

 

[Swifty]

Great job Brian, it was interesting to see the 3 videos and the difference that spring changes made to the running of the engine. The final video of it hitting and missing sounds great.

Paul.

 

[barnesrickw]

This is an incredible engine.

 

[Barnbikes]

Trying to imagine an inline engine. 3 or 4 cylinders all oscillating. Might have to make it a throttle governor though.

 

[Cogsy]

Great work Brian - as always. I'll second what Swifty said about the spring changes. I think I'll play with the intake spring on my Rupnow engine (if I can get it back off my dad for a few days) and see if I can tweak the running/power to get more miss cycles in a row.

 

[Roboguy]

Hi Brian, congratulations on completing an amazing engine!

I am a complete newcomer to both this forum and the hobby, and this build thread is hugely inspiring and educational. Thanks so much for sharing.

I love hit and miss engines, so this engine is definitely going on the someday maybe list!

Cheers,
James

 

[Brian Rupnow]

Every time I build an engine, I discover something.--The thing about the engine refusing to continue running until I removed a coil from the intake valve spring was a "process of elimination" sort of deal. I knew I had spark. I knew the spark was coming at more or less the right time, or the engine wouldn't have run at all. I knew that I had fuel because I could see it moving in the transparent fuel line. I knew that the valve timing was right, or very close to it. The engine had reasonable compression---I could feel it.The sparkplug was good. This was a very typical problem that has plagued me and others before on these small i.c. engines. They start, they run, but only for 20 seconds or so and then they tail off as if they were running out of fuel. Too strong an intake valve spring (on an atmospheric intake valve) was all that was left. It couldn't suck enough air, and since it is the air movement that creates the vacuum to suck fuel up from the tank through Venturi effect, it was running out of fuel. This was an incredible find!!! Everybody that reads this will now be out in the shop dialing in their atmospheric intake valve springs!!!---Brian

 

[toolznthings]

As always, very nice !! Thm:Thm:Thm:

Brian

 

[vascon2196]

Great job Brian...I was there from the beginning and am happy to see such a great running engine.

I will be sharing this with my engineering students.

 

[Mechanicboy]

Brian, how are the vibration of the oscillating engine?