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Engine Valves

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davidyat

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Ved,
OOHHH, I like it! Looks like you are experimenting with using what we learned from the Sun-Planet Engine? For now, until you perfect the design for this one, I think I'll tackle Brian Rupnow's simplified beam engine. I've thought about an IC engine, but the ones out there look like more than I'd like to chew on. Keep me posted on your progress.
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vederstein

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OOHHH, I like it! Looks like you are experimenting with using what we learned from the Sun-Planet Engine?
Yup. My experience with poppet valves is not good. As I've written before, when I tried to make a Webster I had a hell of a time getting the valves to seal even after several attempts. Eventually it went onto the shelf of shame then to an old gear-head co-worker to whom I gifted.

I know it's a crappy combustion chamber design. Generally you'd want a hemispherical chamber or one that causes a "squish". But I'm going for simple here. I don't see why a piece of roundstock shuttling in a reamed hole wouldn't have sufficient sealing. The method works for stirling engines and they have near to no power density. I guess I'll find out.

But if the idea doesn't work, making a new head and incorporating poppet valves shouldn't be too much of an issue.

I have the ignition on order. When I receive it I'll measure it up and figure out how to incorporate it into the design.

...Ved
 

vederstein

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I've been quiet on this for some time, but I have been working on the engine:

The machined components are from the past few weeks and the castings I poured today. (I'm quite happy with how the gears and the camsIMGP2972.JPGIMGP2980.JPGIMGP2981.JPG turned out.)

...Ved.
 

vederstein

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I machined the base casting and assembled the bottom end (minus the piston).

Overall, not bad, but I will need to rethink the connecting rod. My earlier connecting rod design from my Sun-Planet engine (Contessa) worked quite well. I may have to do something similar here.

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vederstein

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Well, now I know spool valves don't work for an IC engine. I got no compression.

I guess I need to redesign the head and try conventional poppet valves.

...Ved.

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teeleevs

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Conventional valves are the way to go but you have to bore the valve guide and seat at the one setting. Picture 1 is of a Hit n Miss engine I built about 10 years ago but I could never get it to run, even the miniature igniter worked, 2 the valves were made in two pieces, head was 10mm about 3/8" And stem 35mm long about 1.350" x 2mm dia 0.078" . Pic 3 a test setup I suspected valve leaks so my friend Gil made up this plate and put the valves under 20 psi pressure and no leaks detected. We will have to re-bore the cylinder and remake piston and rings. 4 I had several attempts to make the rings, they were made from a MAN valve guide. 5 this Galloway was the closest I could find on the internet to an engine my father and I used on the Central Queensland Gem Fields in the 1960s it had no manufacturers markings on it whatever, I did find out that Galloways were made in Queensland under license, 6 the miniature made entirely from memory, no photos or drawings were available.
Ted from down under
 

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vederstein

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Thanks Teeleeves.

As I've written before, I had such a bad experience with my failed Webster that I went with this spool valve concept. I tried several times to make the Webster valves with no luck sealing. I knew the route I took on this design was risky, but it's more within my skill set. I also designed the engine to redesign the head if my spool valves failed.

On contemplation, I have one possible way to recover. I don't know if the leak is from the valve spool or the spool guide. I'll disassemble and put some form-a-gasket to ensure a seal between the head and the valve guide.

I'm not expecting this to work, but it's worth a shot.

...Ved.

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