Mystery engine

[RayW]

I think you're right Graham. A completely new crank seems the way to go. I know what you mean about the odd dimensions. I've done the same myself. Ordered a new pair of gears today so will be able to modify them as necessary to fit the new crank. Will just need to bore out the main and big end bearings then to fit.

[RayW]

The new crankshaft is now finished. I have made the new one a bit more robust than the old one with slightly larger diameter shafts and journal. The webs are identical in profile and dimensions to the old ones, with just the thickness being increased slightly to 1/4". I have added 1/8" keyways as the flywheels were only held onto the old crank by a single locking screw each and had quite a noticeable wobble. Hopefully, boring them out for the larger shafts and adding a keyway will result in a more secure attachment with truer running.
The only other change I made was to adjust the length of the shafts either side of the webs as the old crank was very short one side and unnecessarily long the other, and the short side would not have left much room for a key.

[RayW]

Made good progress over the last few days. New gears machined to size and fitted, with the roller for operating the exhaust valve pushrod on the back of the large gear.
Flywheels bored out to fit new crankshaft and keyways cut.

[RayW]

Sorry for the long break between updates, but other things have got in the way. I have been making steady progress in moving towards getting the engine running, and I am very nearly (but not quite) there now. One big setback was that my nice new crankshaft failed, as my attempts at silver soldering were clearly inadequate. The new one was made with minor differences to the first one, with slightly longer shafts and a wider big end. With the benefit of much greater heat, the solder penetrated all of the joints well, making a really strong job.

My eventual intention is to use hot tube ignition but for first attempts at running, I have fitted a glow plug, as my first efforts with a hot tube resulted in some very impressive flames and a strong chance of me burning the workshop down! I will leave that to another day when the weather is warmer and I can try again outside.

The attached photos show the pipework for the gas supply. The burner has been removed from its base for now and a temporary steel plug used to seal the hole. The brass valve has been modified as on my previous engines to give much finer control of the gas supply. As both air and gas valves operate atmospherically, ie. by suction of the piston in the cylinder, getting a correct balance of the gas/air mixture is very much a matter of trial and error.

I made a new air valve for the top of the cylinder as the old one was extremely crude, and actually dropped into the cylinder after the retaining nut unscrewed itself when I was spinning the engine over with an electric drill. Despite the horrendous noise, the cylinder was unmarked, and the piston just showed a tiny mark which was easily removed with a file.

Over the last few days, I have managed to get the engine firing with the drill, and, on a couple of occasions, running very briefly on its own but I still can't get it to keep running yet. As the air and gas valves operate atmospherically, the only valve timing to set is the exhaust. Based on other engines, I have it set for the exhaust valve to be fully closed by TDC. Compression is very good with strong bounce back.

[Alyn Foundry]

Hi Ray.

Your little Leek is looking very nice, well done on the restoration.   

Having two “ atmospheric “ valves will, quite literally be, double trouble. Having thought about the problem since your last email I wonder if you were to put a slightly heavier spring on the gas valve and allow the depression in the cylinder to make it act like a form of “ demand “ valve? This would ensure that more air is present in the cylinder.

Since we last chatted another water cooled, four stroke Leek has surfaced….

Cheers Graham.

[RayW]

Hi Graham, that is definitely an option to try. I don't know at the moment which way the mixture is out - too much air or too much gas. I have the adjustable regulator on the gas bottle turned down to the point where the gas is almost inaudible. What I really need to do is test the mixture with your candle method, but that would be quite awkward, given the short vertical exhaust outlet. I designed the new air valve to allow more air in than the old one.

I am intrigued by the other Leek that has surfaced. Do you have any more info or photos?

[Alyn Foundry]

Here she is Ray,  in “ as found “ condition.

Heavily modified with a pair of “ flywheel crank “ wheels from a very old motorcycle engine. You can see the wrought Iron ignition tube and a generic Dynamo for Radio battery charging. I’m pretty sure the Dynamo is an EEC made in London.

I supplied the flywheel to help restore the Leek to its former glory.

Cheers Graham.

[Jasonb]

Ray if you use one of those lighters with the extended end then that will work with a vertical exhaust and you won't go dripping wax all over your engine. Cost about a pound

[RayW]

Thanks Jason. I've searched everywhere for candles with bent flames!

[RayW]

Discovered that a bent piece of 1/4" copper pipe fitted into the exhaust vent, so was able to try the candle test and got a nice strong blue flame with virtually no gas. Tried the engine at that setting, but refused to fire. Played around a bit more with the gas pressure and finally got the engine to run repeatedly for a short time when started with the electric drill. A few issues came to light such as things that needed tightening up, in particular the big end bolts, which accounts for the knocking heard on the video. I need to make some new bolts that are long enough for two nuts on each.
The engine runs pretty fast and there is no real way that I can see of slowing it down, as the slightest adjustment of the gas needle valve stops it.
Still work to do, but really pleased with progress today. This is a link to the Youtube video.
<a href="https://www.youtube.com/watch?v=lLJFgnXtzpA" target="_blank">http://www.youtube.com/watch?v=lLJFgnXtzpA</a>

[Alyn Foundry]

Well done Ray….

Having had zero knowledge of the use of glow plugs in this application I wonder if you might get different results from the tube ignition?

Cheers Graham.

[RayW]

Yes, varying the position of the hot spot on the tube should alter the timing. Now that I have sealed all the potential leaks, it might be worth trying with the hot tube again without the risk of another inferno!

[Admiral_dk]

A major milestone reached - that must feel good     

[RayW]

Finally gave in and converted to spark ignition with battery and trembler (buzz) coil. With a new gas bottle connected, it started and ran better, and for longer, than it has ever done before. I now also have the facility to adjust the ignition timing to find the best running position.

At the moment, there is no cooling system and after a few minutes running, the engine got so hot that some of the solder on the water jacket started to melt! I will experiment to see if retarding the ignition, which is currently at TDC, will make it run cooler. In the meantime, I am on the look out for a suitable cooling tank.

[Jasonb]

Beans for tea then

Good to know it's running better but shame you had to resort to a plug.