Hello all. Here's a strange one. I'm hoping someone can help me identify it. It's about 4" tall, 2 stroke, displacement in the area of .55 cid. There are no makers marks. The crankcase looks like an aluminum home machine job BUT the cylinder and piston/rod/crankshaft combo look professionally produced. It has a rear disk induction. The piston is EXTRMELY heavy (most likely like the Enya meehanite/iron combo). There is one exhaust port (opposite in the picture) and the bypass is actually on the outside of the cylinder (the vertical strip on the outside of the cylinder in the picture). The exposed shaft (left side of picture) is 5/16" in diameter and the other side (right side in the pic) is actually a provision for a needle valve or carb setup. The crankshaft runs in dual ball bearings. The engine overall I would say comes close to 2lbs in weight. It has a glow plug in the head BUT I suspect that originally it might have had a spark plug ignition.

Also, the thread in the glow plug is rather odd because I tried a plug from my Enya .09, Veco .19 and a newer O.S. .25Fp engine and the threads don't fit.

Any help or info on what this engine might be would be appreciated.

Looks like a one off homemade engine?

Back in the 40's there was a bigger spark plug than 1/4"-32. There may have been some big glow plugs?

It could be home-made BUT here's the odd things. The case is rather rough machined and of a rough quality as compared to the crankshaft/piston/cylinder assembly. Unless of course the engine was tinkered around with by 2 people. The 'master machinist' did the reciprocating assembly and a 'home machinist' at some later stage tried to do the case. A couple more interesting features of the engine are: even though the piston is meehanite (or iron for all I know), the connecting rod is aluminum and bushed at the lower end with a bronze bushing. Seems sort of odd to have a piston that weighs almost 1/2lbs and do an aluminum connecting rod.

Also, on an off topic, I would guess this engine is of the 1940s vintage. With this in mind what were the rpms that the model engines in the 1940s run? Anyone know? I'm referring to stuff like Ohlson & Rice, Vivell, Orwick, Foster, etc. The reason I ask is that I'd like to install an r/c carb on the engine and was wondering on what would be a good carb size to run on it. Even though the engine is a .55 size I'm leaning towards something off of a .35 or .40 modern engine to compensate for the old engine's single bypass as opposed to the new engines' schneurle porting and therefore inferior volumetric efficiency as compared to the newer engines.

w8ye, the glow plug on the engine actually has about the same diameter of the threaded part as the one in my Enya .09 or Veco .19 BUT is just a tad different so that it doesn't fit....just a teeny bit different thread.

It's most likely 1/4"-28 instead of 1/4"-32

Meow:

The cylinder looks a lot like the OK 60, but if it is it should have the 3/8-24 thread for the plug.

If you don't have thread gauges take the engine to your llocal hardware store that has a good selection of fasteners. By trying different SAE and metrics you should be able to find what the thread is.

Bill.

PS: See my post [link=http://www.rcuniverse.com/forum/m_3884973/anchors_3885157/mpage_1/key_/anchor/tm.htm#3885157]here[/link]. wr.

w8ye, yeah you might be right, it most likely is 1/4"-28 (coarser) insted of the finer 1/4"-32. William, I think that's what I'll try doing to get the exact thread type. As for the cylinder being like an OK .60 you might be right. Is it possible that IT IS the cylinder from an OK .60? The .55 displacement that I stated is a somewhat rough figure. I was able to measure the bore accurately with my Starrett (just to brag a little hahaha)...but as for the stroke I just got a pretty good but rough idea. And I came up with .54 as the displacement. This of course is closer to .60 I'm sure since I didn't take into account the fact that the piston top is somewhat sloped. It's sloped/cut out on one side to make the exit of exhaust gasses easier and it is sloped on the opposite side as well to ease the passage of the fresh charge into the combustion chamber. PLUS, there is a good amount of space left at the top of the chamber when the piston is at TDC (although I didn't actually cc it to get an exact figure). In any case it looks like the compression ratio is not all that high and so that's why I perhaps though that it might have been an ignition engine originally. I have my doubts as to whether it will even run with a glow plug.

Anyways, any thoughts about the rpm range on these old engines and whether a 'modern' .35 or .40 r/c carb would be good for this engine?

Oh, I forgot in regards to the space left at the top in the chamber when the piston is at TDC. Since the case was 'home-machined' it is possible that originally the compression was meant to be higher but whoever machuined the case just didn't mill it enough.

Being as it is a piston ported engine, changing the cylinder height may be critical to the timing. You might better check your timing?

Enjoy,

Jim

Well, I did some internet legwork and look what I came up with. I think this might be the engine, looking at the construction of the cylinder barrel (i.e. the single outside bypass). Of course the case looks different as I assume was made later by another machinist but.....so w8ye is most likely right that it's a one-off sort of a thing although it looks like the plans were published.

Ahh, that's what was so good about the old days (heh heh heh), you could build all these things. I have some copies of modelling magazines from the 1940s and 1950s and some of the stuff and plans in there are truly amazing. Too bad that's no longer the case these days and so much of the model stuff is so cookie cutter.

Intake period in a piston ported engine must not be more than 90 degree or the engine will lost effect if more than 90 degree in intake period.

Jens Eirik

Those days aren't gone, they are just different now. There are several kits for constructing brushless electric motors and lots of folks making their own from CD rom conversions. The average modeler isn't going to tool off any internal combuston motor that will produce as much power as a commercialy produced one unless he is a master machinest. Lamenting the change in R/C reminds me of some car enthusiasts who lament the death of the carb and the rise of fuel injection. Car enthusiasts today are extracting far more HP percentage wise than their predicessors ever did and instead of drilling out a carb jet they are tailoring a 128 bit 3 dimensional fuel map. Model aircraft are no different, the same sort of work is being done, just with the technology of the time.

The " Way back in time machine is no longer working " .

Subarubrat, you're opening Pandora's box here but here we go: I wasn't lamenting but disappointing in the relative lack of variety these days. Before if you wanted an off the shelf engine, you got one, if you wanted to machine one from plans you could. These days not so many plans out there but lots of off the shelf stuff. Nothing wrong with 3 dimensional fuel maps BUT when I go buy a new Jaguar I want a Jaguar not a thinly disguised Ford platform......when I go to get a Rolls I want a Rolls and not a thinly disguised BMW or VW or whatever the case may be in that particular example. See where I'm going?......Just like with wine and women, nothing wrong with variety. It'd be pretty boring in the world was full of brunettes with C cups.