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Does anyone know what this is?

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Allen Smithee:
[as I don't know what this is I couldn't decide where to post it - if you want to move it to another section please do so!]

A fellow RC flyer in my club handed me this today. Apparently a client of his (a retired surgeon) now sadly has Alzheimers, and his wife gave him this in case he could do anything with it:





Initial examination suggests it's a 4-stroke diesel machined from bar stock rather than castings. I haven't measured it [yet] but I'd guess at around 10cc. It seems to have a one-piece steel cylinder with alloy block and head. There is no provision for a glowplug, and the tommy-bar driven feature at the back of the head seems to open or seal a small blow-hole (perhaps like the "decompression device" found on some vintage bikes for starting?). There is a conventional airblead carb and a substantial (unfinished) pegged prop-driver/spinner nut assembly.

It seems to be almost complete, missing only pushrods, rockers, rocker mountings, tappets, throttle lever and exhaust pipe/silencer plus the completion of the propdriver/spinner-nut.

Does anyone recognise this engine? 4-stroke diesel aero engines aren't exactly common, so is it a known design or something he did himself? If it's a known design does anyone have the drawings of know where I could get them from?

I'd like to finish this engine off and get it running. All the missing bits are things which I could design and make without the original drawings because I can see what was intended, but it would be good to have the drawings if they're available...

All help appreciated

AS

Admiral_dk:
My first thoughts where a that the bottom end looks a bit like a Saito .... but not the top end.

I'm sure it's a CI (Compression Ignition ~ diesel) engine and it is supposed to run on a mix of ether, kerosene and Castor oil - you might add an Ignition improver (1-2%). The Tommy Bar it the compression adjustment in a special configuration I'm sure Greg (Diesel Pilot) has used many times when he converted Glow Plug engines to CI.

It could be a home design, from a magazine or a bought "kit" / drawing.

Allen Smithee:
I'm familiar with model diesel 2-strokes, but the only 4-strokes I've seen were the experimental one Laser did (which I don't think went into production) and the curious Saito one that was supplied as a partially disassembled "kit". Both of these had glowplugs for starting.

The tommy-bar doesn't set a contrapiston (there is no contrapiston) - it has a tapered nose the seems to just seal a very small blowhole in the head. The blowhole is about 0.25mm dia, which is why I think it might be a decompression device to allow the engine to be spun-up on a starter.

AS

dieselpilot:
I don't recognize it. I would guess it was his own effort. There just isn't much out there in four stroke diesel. I'd love to see larger photos, the craftsmanship looks excellent.

Decompression device in an engine this small is unnecessary. If it is a diesel and has so much compression a starter won't turn it over, it likely has excessive compression ratio.

Admiral_dk:
Greg I know it isn't a contra piston in a four-stroke and that it is just about the size off a normal Glowplug - but what are they called (I know you have made some) ?

Could it be that in this case it is the same but made in such a way that if you lift it almost all the way out it opens to the atmosphere so you can "Blow out" a "drowned" engine ?

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