Model Engine Maker

Engines => Restoration of Model Engines => Topic started by: RayW on September 26, 2020, 02:24:49 PM

Title: Mystery engine
Post by: RayW on September 26, 2020, 02:24:49 PM
This lovely little hot tube engine came my way today via eBay from a seller who lives only 10 miles away.

It appears to be very early, possible Circa 1900, but the previous owner has been unable to find any information about it despite many years of searching. Many of the steel parts are heavily corroded or worn. The gears show evidence of extensive wear, with the teeth on the crankshaft one being worn almost to points, and missing one tooth.
The previous owner has fitted a new piston, but, apart from that, he thinks that everything else is original.

Amongst the most interesting features, there is what appears to be an air inlet valve on top of the cylinder.The hot tube is fitted with a long, hex headed screw which, apparently, adjusts the timing.
The connecting rod is bellied in shape, tapering to each end, very like would be found on a steam engine.
The exhaust valve is operated by a flat, L shaped push rod driven by an eccentric pin inside the large gear.
I understand that the inside of the cylinder head is hemispherical.

If anyone can throw any light on the identity of this little engine, I would love to hear from them.
Title: Re: Mystery engine
Post by: Jo on September 26, 2020, 03:04:21 PM
It looks a bit like a slightly modified Schoenner Gas engine

Jo
Title: Re: Mystery engine
Post by: Jasonb on September 26, 2020, 04:11:03 PM
The flywheels and base doo look a lot like the schoenner engines but the gears on this make it a 4-stroke cycle rather than two, could have been heavily modified as everything from the cylinder back does not look like castings have been used.
Title: Re: Mystery engine
Post by: RayW on September 26, 2020, 04:13:00 PM
Yes Jo, I did consider that, but nothing on my engine seems to resemble the Schoenner one but I am pretty certain it must be pre -1900. The previous owner spent years trying to identify it but couldn't find anything.
I am convinced it must have been a kit as parts such as the base, body, valve chest and hot tube are all castings rather than home made.
What I would like to do is to replace as little as necessary to get it running, while still keeping the old patina and wear. The gears will almost certainly need replacing, but other than that, everything else appears to be functional, apart from a few valve springs that will need replacing.
The previous owner made a new piston as that was missing, but he did not fit any piston rings, so I may have to see how good compression is once it has all been stripped down and re-assembled.
 
Title: Re: Mystery engine
Post by: RayW on September 26, 2020, 04:18:46 PM
Just to clarify Jason, the base, body, valve chest, hot tube, flywheels and cylinder are all castings. The crank webs are heavily pitted, but they could also possibly be cast.
Title: Re: Mystery engine
Post by: Jo on September 26, 2020, 04:25:30 PM
The base looks identical to the Schoenner except that it has had underneath cut away. The main body and bearing caps are identical as is the flywheels.

My guess is someone converted it to a hit and miss at some time.

Jo
Title: Re: Mystery engine
Post by: RayW on September 26, 2020, 04:41:34 PM
I have checked the base and the cutaways are definitely original as the cast surface is clearly visible.
Title: Re: Mystery engine
Post by: Jasonb on September 26, 2020, 04:48:02 PM
I can't see any form of latching to suggest it is Hit & Miss governed, just 4-stroke hot tube ignition.

The fact that the non schoenner parts are all bronze could mean they were cast later possibly at home.

Where is that Graham when you need him?
Title: Re: Mystery engine
Post by: Jo on September 26, 2020, 04:49:48 PM
This is the British Modelling and electric Co copy of the Schoenner engine - it has a cut away cast base.

As these engines were designed to run on town Gas when that was phased out the only alternative was to run on acetylene which is not easy to come by (safely  ::) ) My guess is someone published a modification at some point...

Jo
Title: Re: Mystery engine
Post by: RayW on September 26, 2020, 05:09:37 PM
Well done Jo. I think you may have cracked it! Do you have any other info about the British Modelling and Electric Co?
I have been probing about in the water jacket holes with a bent wire and I strongly suspect that under the (definitely home made) copper water jacket, I will find a finned air-cooled cylinder.
Title: Re: Mystery engine
Post by: Jo on September 26, 2020, 05:16:31 PM
Sorry that is the only pic I have of that engine.

You may be aware that Bruce engineering did a copy of the schoenner engine known as the AGE which I have the drawings for and Surus has the set of castings  :-X

Jo
Title: Re: Mystery engine
Post by: Jasonb on September 26, 2020, 05:17:02 PM
Ray, take a look at this thread, they were located in leek which may sound familiar

http://www.modelenginemaker.com/index.php?topic=7414.0
Title: Re: Mystery engine
Post by: RayW on September 26, 2020, 05:25:27 PM
Thanks Jo and Jason. You beat me to it Jason. I have just been reading Graham's thread on these engines, so it appears I definitely have a Leek (very appropriate as Graham lives in Wales!|).
Title: Re: Mystery engine
Post by: Alyn Foundry on September 26, 2020, 07:49:24 PM
Hi Ray.

Indeed you do!!

This is the second one I've seen in my lifetime. I actually restored the first for a friend of a friend.  ;)

Personally I'd do the least amount of restoration possible as it has a beautiful patina.

Cheers Graham.
Title: Re: Mystery engine
Post by: Alyn Foundry on September 27, 2020, 11:35:50 AM
Having slept....

These engines were toys, available in 3 sizes ( working from memory ) 3/4" 1" and 1,1/4" bore with a 2" stroke. Suffixed as numbers 1, 2 & 3.

Designed to run on Town gas. Some period advertising mentioned an " Ideal " shopfront display and capable of speeds up to 500 RPM. Power output minimal.

By converting the engine to a four stroke cycle the power output could be much greater and capable of driving a small Dynamo for the charging of radio batteries.

Your engine Ray has seen a very well executed conversation from atmospheric to compression before ignition principle and quite probably worked for its living.

I did notice the counterbalanced crank, a very useful addition.

Cheers Graham.
Title: Re: Mystery engine
Post by: Jasonb on September 27, 2020, 12:11:13 PM
So what's the thinking on the induction side of things?

Did the flat flange with a bit of soft solder on it connect to the gas supply and draw in a small amount of gas with the air coming in via the top mounted valve on the cylinder or did air and gas enter into the flange through a missing part much like the Sphinx with the exhaust going up out of the vertical spigot.

The two inlet valve springs look quite thick for atmospheric opening but may be OK.

J
Title: Re: Mystery engine
Post by: Alyn Foundry on September 27, 2020, 01:36:24 PM
Hi Jason.

Your guess is as good as mine. Ray did point out that the previous owner had done some minor restoration, the heavy spring on the inlet would not work atmospherically. So with perhaps a positive pressure of gas on that valve and the top acting as air only might work.

If it were me I'd opt for a " Sphinx like " arrangement and totally ignore the top valve altogether.

I'm guessing readers can see the close similarities to the R.L.E. ? They should because it was my own engine, pictured below that was the inspiration.

I've worked on many of the larger HP Leek engines over the years, one feature was the reduced diameter of the crankshaft inside the main bearings. Reduce end float ??  :)

Cheers Graham.
Title: Re: Mystery engine
Post by: RayW on September 27, 2020, 02:47:48 PM
The previous owner did point out that a lighter inlet valve spring would be needed and the atmospheric valve also needs one as well. My preference would be to leave the gas and air inlets separate initially to see how well that works.

I have my doubts as to how effective the water jacket would have been as there seems to be very little clearance inside, particularly if the cylinder retains its fins as I suspect. It will also need a proper threaded connector soldered on underneath as there is just a small hole and a rough patch of solder at the moment.
Judging by the wear on the gears, which are 32 to 16 ratio, the engine has done a lot of work in the past.

Title: Re: Mystery engine
Post by: RayW on September 29, 2020, 05:39:54 PM
Been having a closer look at the engine today. I had assumed that the spindle for the large gear was badly worn as the gear was wobbling about. On closer inspection, I discovered that the locking nut for the shaft, inside the bracket bolted to the engine bed, was very loose. On tightening it up, the gear now runs true with no wobble.
I had concerns that should I decide to replace the badly worn gears, I might have trouble removing the flywheel to access the smaller gear,  but to my delight, on undoing the locking grub screw, the flywheel slid off the crankshaft easily.
There is quite a wobble on both flywheels, but this seems to be worse when the grub screw in each flywheel hub is tightened, indicating that the flywheel bore may be worn, allowing it to tilt slightly when the screw is tightened. I will have to have a think about the best way to sort this out. I could either plug and re-bore the flywheel or add another grub screw to the opposite side to counter the tilt. Either way, I would want to do the modification as unobtrusively as possible. The flywheels have been re-painted in the past so should not be a problem to blend in any repairs.
Title: Re: Mystery engine
Post by: Alyn Foundry on September 29, 2020, 09:28:33 PM
Hi Ray.

Whilst the grubscrews would have been more than adequate to secure the flywheels for an atmospheric operation I feel they would work loose very quickly under the present situation.

I personally would make a replacement crankshaft and put in keyways. You can then keep the original crankshaft for posterity.

My own engine had its shafts threaded to 3/8" BSW and the flywheels were literally clamped between two nuts. ( common practice for the home machinists of the time ) My good friend Martin replaced them with plain shafts and keyways. We used the original crankshaft on this occasion as we didn't think anyone would like to see threads!

At the end of the day the choice is yours and what you do will depend upon how you're going to use the engine. A simple solution would be the use of thin Steel shim to " pack out " the discrepancy.

Cheers Graham.
Title: Re: Mystery engine
Post by: RayW on September 30, 2020, 10:24:32 AM
Hi Graham,
I am reluctant to replace any more parts than necessary for now, to retain its lovely aged look. As far as I have been able to see, the bearing surfaces and crank journals, and the areas under the flywheels all remain in pretty good condition, even though the webs and exposed areas are pitted. The same applies to the exhaust valve operating bar which is heavily pitted, except where it passes through the two brass guide brackets.
Even the gears, which are heavily worn still run OK, with the missing tooth on the crank gear seemingly not making any difference.

The first job I need to tackle is the three valves (exhaust, gas inlet and air inlet). All need re-seating to try and get some compression. When I turn the engine over, there is plenty of air blowing out from various places so it looks as if the new piston is a good fit in the cylinder, even though it has no rings.
Title: Re: Mystery engine
Post by: RayW on November 08, 2020, 04:14:56 PM
The attached article, which is reproduced by kind permission of Patrick Knight, the Editor, has appeared in the December 2020 issue of Stationary magazine.
Title: Re: Mystery engine
Post by: RayW on January 27, 2021, 12:37:49 PM
Tried some much lighter springs on the gas and air inlet valves but little compression, although there is a little suction through the gas valve and a light puff of air from the exhaust valve.

Having dismantled the valve chest, it is clear that I am going to have to make completely new valves and fit new valve seats. As can be seen from the photos, the exhaust valve seat (on the right in photo1) is a very off-centre copper plug. The exhaust valve (seen below) is very crude and badly corroded. For some strange reason, the section below the head has been filed to a triangular section. The inlet valve chest (on the left in photo 1) also has an inset copper plug and, again, the valve is badly corroded and such a loose fit in the valve guide that it just wobbles about. It is also slightly bent at the head end. It looks possible that these crude valves may have been made from bolts or screws as they have quite deep slotted domed heads.

As will be seen from photo 2, the atmospheric air inlet valve, which sits on top of the cylinder, is also very crudely made and is unlikely to work properly, so a replacement will need to be made.

The hot tube, which I suspect was never fitted to the engine when it was running as it show no signs of ever having been heated, is fitted into a removable boss, which is screwed into the cylinder head. I spent a considerable time trying to identify the thread in the cylinder head which is the same as that where the valve chest screws into the cylinder. I established that it was 3/8" x 26 TPI but couldn't find that thread listed in my charts, until I discovered a tap in my "Miscellaneous Taps" box marked B.S.A 3/8" x 26 TPI B.S.B, or British Standard Brass. I am hoping that I will be able to open the cylinder head thread out to M10 x 1 to take a standard CM6 plug.

The other two photos show the inside of the cylinder head and the piston in the cylinder. The piston is the only new part made by the person that I bought the engine from.



Title: Re: Mystery engine
Post by: Alyn Foundry on January 30, 2021, 12:09:18 PM
Hi Ray.

My own engine appeared to have had " converted " fixings for the valves too, where possible I left them in situ.

You're not alone..... Yet another engine has come to light in almost " as found " condition. Driving an EEC dynamo. Few today would realise that they were needed to keep Radio batteries charged for the valve/tube heater circuit.

Cheers Graham.
Title: Re: Mystery engine
Post by: RayW on January 30, 2021, 04:39:14 PM
That's rather nice. Where did that one appear from?
Title: Re: Mystery engine
Post by: Alyn Foundry on January 30, 2021, 07:25:56 PM
That's rather nice. Where did that one appear from?

Hi Ray.

Yet another " eBay " discovery....

 :cheers:
Title: Re: Mystery engine
Post by: RayW on January 30, 2021, 09:10:42 PM
Yours now?
Title: Re: Mystery engine
Post by: RayW on January 31, 2021, 05:37:28 PM
The inlet and exhaust valves were in such poor condition that I made completely new ones and re-cut the valve seats. Both now seem to be sealing OK but still almost no compression, so the inlet valve is not being sucked open, even though I have fitted a much lighter spring..
Made a cylinder head gasket and one between the two halves of the valve chest today and those areas now seem air tight. There is still no compression, however, as the air valve on top of the cylinder is leaking badly, and is so crudely made that the only option seems to be to make a replacement. The one big problem I have is that I have been unable to identify the thread where it screws into the cylinder. The OD of the thread on the valve is 0.295" and the pitch appears to be 20TPI. I have searched the internet, but cannot find anything that matches this.
If I can't identify it, the only option will be to cut off the thread from the valve and solder it to the new one.

I have now re-tapped the thread in the cylinder head where the hot tube was fitted to accept a standard CM6 spark plug.
Title: Re: Mystery engine
Post by: RayW on February 05, 2021, 12:29:23 PM
After a bit more work on the valves. I managed to get pretty good compression, with the gas and air inlet valves both opening and closing under suction.

Decided to pull out the crankshaft today to see if it was salvageable and just as well that I did, as I found that one web was twisting slightly on the main journal. As can be seen from the attached photos, all of the bearing surfaces are in pretty poor condition with lots of pitting. The webs are also heavily pitted all over, although a lot of the pitting is not too deep.

The crank is of made-up construction, with two separate main shafts, each being either press fitted, or soldered into its respective web. The ends of each shaft are reduced to a similar diameter to the main journal where they pass through the web. It is unclear whether the collars adjacent to each web are part of the shafts, or part of the webs themselves.

One thing that puzzles me, as with the rest of the engine, is the odd mixture of dimensions, which do not seem to comply with any fractional or metric ones, with a few exceptions. Bearing in mind that this is an early English engine, one would expect most to be fractional, but, for example, the main bearing diameter is 0.349" which falls between 11/32" and 23/64". The webs are 0.230" thick which, again, does not correspond with any standard thickness material.

As far as I can see, I have two options;

1) Make a completely new Crank, copying the existing counterbalanced design, but using standard size materials, eg 3/8" diameter shaft and 1/4" thick webs and adding keyways to the shaft and flywheels, which are currently retained only by a locking screw.

2) Try to dismantle the existing crank and re-use the webs, re-boring them and just cleaning up the worst of the surface pitting, but leaving evidence of their age.

Title: Re: Mystery engine
Post by: Alyn Foundry on February 05, 2021, 01:34:29 PM
Hi Ray.

I made the suggestion of replacing the crankshaft a few posts ago and still stand by it. Rather than perhaps destroy its history you can keep hold of the original and make a decent replacement for running.

With regard to the " odd measurements " well.... I do the same, make one part fit the next.   ;)   It seems to have been common practice back in the day of small power engine building.

Regarding that latest engine find, no not mine but a member of the FB group. So that's the third one I've seen now !

Cheers Graham.

Title: Re: Mystery engine
Post by: RayW on February 05, 2021, 03:51:31 PM
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.

Title: Re: Mystery engine
Post by: RayW on March 01, 2021, 05:20:55 PM
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.

Title: Re: Mystery engine
Post by: RayW on March 06, 2021, 05:46:50 PM
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.
Title: Re: Mystery engine
Post by: RayW on November 01, 2021, 12:52:08 PM
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.


Title: Re: Mystery engine
Post by: Alyn Foundry on November 01, 2021, 04:11:10 PM
Hi Ray.

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

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.
Title: Re: Mystery engine
Post by: RayW on November 01, 2021, 05:14:01 PM
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?
Title: Re: Mystery engine
Post by: Alyn Foundry on November 01, 2021, 05:37:38 PM
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.
Title: Re: Mystery engine
Post by: Jasonb on November 01, 2021, 06:26:55 PM
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

(https://ae01.alicdn.com/kf/H16dced093ee342cd8b61ed805835f238I/1PC-Candle-Lighter-Butane-Refillable-Plastic-Torch-Lighter-Multi-purpose-Kitchen-Fireplace-Pilot-Light-BBQ-Stove.jpg_Q90.jpg_.webp)
Title: Re: Mystery engine
Post by: RayW on November 01, 2021, 09:00:13 PM
Thanks Jason. I've searched everywhere for candles with bent flames!
Title: Re: Mystery engine
Post by: RayW on November 02, 2021, 02:37:51 PM
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.
https://www.youtube.com/watch?v=lLJFgnXtzpA
Title: Re: Mystery engine
Post by: Alyn Foundry on November 02, 2021, 04:08:17 PM
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.
Title: Re: Mystery engine
Post by: RayW on November 02, 2021, 05:01:48 PM
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!
Title: Re: Mystery engine
Post by: Admiral_dk on November 02, 2021, 08:32:04 PM
A major milestone reached - that must feel good  :ThumbsUp:    :cheers:
Title: Re: Mystery engine
Post by: RayW on December 15, 2021, 03:52:48 PM
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.
Title: Re: Mystery engine
Post by: Jasonb on December 15, 2021, 04:59:02 PM
Beans for tea then ;)

Good to know it's running better but shame you had to resort to a plug.
Title: Re: Mystery engine
Post by: Alyn Foundry on December 15, 2021, 06:16:08 PM
Jason has a point.

One of my favourite cooling tanks was made from a large empty home brew Malt extract tin. They have a plain band at each end with corrugated centre portion. They look remarkably similar to the cooling tanks of old. Some 3/32” diameter rod with a hook at one end can then be used to anchor the tank in position.

The gas…. We found out years ago that stale gas didn’t help the running of our small power engines, particularly hot tube ignition, something to do with the “ higher Oelfins “ …. See Wikipedia. These higher Oelfins get used up during the early stages leaving the less volatile “ lower Oelfins “ behind. This information may well have been corrupted by my mind because I was told about it many years ago lol.

I’m of the opinion that you’d need to advance your ignition rather than retard it to reduce the temperature Ray.

Cheers Graham.
Title: Re: Mystery engine
Post by: RayW on December 15, 2021, 07:44:52 PM
Thank you Jason  and Graham. I was looking at military brass shell cases for a water tank but the tin can option is worth considering. That's interesting about stale gas Graham. I think most of us assume that gas remains the same at the start and end of a cylinder.
As regards ignition timing, I will definitely try advancing first to see if that helps with the hot running. I still have strong suspicions that there is actually a finned air cooled cylinder under the water jacket and it will be interesting to see just how effective tank cooling will be given the tiny gap between the cylinder and the jacket.
As far as the plug is concerned Jason, the cylinder head is tapped to take either a spark plug, glow plug in an adaptor, or hot tube. I have all three so I can experiment with all three options.
Title: Re: Mystery engine
Post by: RayW on December 19, 2021, 03:46:33 PM
The engine has been starting really easily and running nice and steadily with the spark plug so I decided to tackle the last big job. Checked the water jacket for water tightness, and as I had anticipated, it leaked around the white sealant between the copper jacket and the cylinder casting. This had gone very hard and brittle where it had oozed out and could be broken off with my fingers. Having cut off the excess, I found that the sealant below was still slightly rubbery, with some air holes in places. It looked as if whatever the sealant was, it had been poured into the gap and allowed to overflow. I decided to remove it all as it clearly needed replacing. It completely filled the groove between the first metal boss and what appears to be the first fin of an air cooled cylinder.

This confirmed my suspicions that there is actually a finned air cooled cylinder inside the jacket.The first visible fin has had a flat filed on the bottom, presumably to allow water to circulate, and the next fin has a small notch for the same purpose.

I am now faced with a big dilemma. Do I simply re-seal the open end of the jacket by filling the space with a suitable sealant (not sure what) or do I now go all the way and remove the jacket and return the engine to its original air cooled form? I would obviously be taking a gamble that any damage to the fins was relatively minimal and could be easily rectified. The jacket appears to be firmly stuck at the cylinder head end and where the valve chest and atmospheric valve screw in, so the chances are that it could be irreparably damaged in being removed.

I personally favour converting back to air cooled format, but I wonder what other members think?

Title: Re: Mystery engine
Post by: Jasonb on December 19, 2021, 04:52:07 PM
Air cooled would be nice, fins could certainly be patched up with JBWeld.

Likely to be similar sealant on the rest unless they did some soft soldering once it was in place and that may be what is holding it firm. Probably boss white or plumbers mate that was used.
Title: Re: Mystery engine
Post by: RayW on December 19, 2021, 05:28:50 PM
The sealant definitely seems to have been some sort of liquid, judging by the air holes in it - perhaps some sort of liquid latex?
At the cylinder head end, as you will see from the photo, the jacket wraps around the cylinder, and there appears to be a gasket, or it could be some sort of sealant, between it and the face of the cylinder so it may be possible to slide a very thin sharp blade in to cut through that. Just in case the fins are too badly mutilated, I would like to try and preserve the copper as undamaged as possible, just in case I need to re-fit it.
Title: Re: Mystery engine
Post by: RayW on December 20, 2021, 04:23:57 PM
I managed to remove the copper water jacket intact and with only minor damage and look what I found underneath!!
Exactly as I had suspected (and hoped) all along, a nice original finned, air-cooled cylinder. A few notches had been filed in the fins to allow water circulation, but, as you will see from the first photo, that was unlikely to happen now, given the amount of rusty sludge between the fins. Obviously though, water cooling had been used at some stage, and apparently for quite some time, for that amount of sediment to accumulate.
The damage to the fins is minor and easily repairable with JB Weld.
The boss where the valve chest is located had been rounded off to match the profile of the fins and to accommodate the water jacket, so I have milled it flat to ensure a good sealing face.
There is an unmachined boss on the opposite side, which, I believe is where a flame ignition port would be. I am sure Graham and Co will correct me on that if I am wrong.
Title: Re: Mystery engine
Post by: Alyn Foundry on December 20, 2021, 06:06:37 PM
Hi Ray.

I’ve zoomed in on the flame port boss, it looks as though it might have been plugged? It could be an ideal place to mount a pivot for a small fan to aid the cooling of the cylinder.

My original Leek when I converted it to spark ignition ran really hot but never seized up, no fan either.

Cheers Graham.
Title: Re: Mystery engine
Post by: Jasonb on December 20, 2021, 06:33:55 PM
Would be the right place for the flame ignition port as per the one in this thread

https://www.smokstak.com/forum/threads/leek-british-engineering-flame-ignition-toy-engine.163135/
Title: Re: Mystery engine
Post by: RayW on December 20, 2021, 06:57:41 PM
The boss is definitely as cast and has not been machined or plugged. Is that your Leek Graham? If so, could you give me more details of the ignition system you are using, as I can't see a spark plug. Seeing how blocked the water jacket was, it's no wonder it was running so hot as the heat had nowhere to escape. Hopefully, it will run much cooler now.
Title: Re: Mystery engine
Post by: Alyn Foundry on December 20, 2021, 08:04:08 PM
Hi Ray.

If you zoom in on my previously posted photo you’ll just see the end of the insulator and knurled nut for the HT lead, behind the top air valve. My engine had been threaded 1/8” BSP I modified a 10 mm sparkplug by cutting the end off and re threading it. The ignition was a homemade trembler, inside the wooden box and was timed by that little eccentric on the sideshaft.

It worked really well as an atmospheric and would “ pop “ away for hours. The spark was timed to start just as the piston passed the port, halfway down the stroke. Needless to say it never ran at all with the “ proper “ flame ignition but was really happy on Propane and spark.

Cheers Graham.
Title: Re: Mystery engine
Post by: RayW on December 20, 2021, 08:28:57 PM
I can see it now thanks Graham. I had assumed that you had put the plug in the cylinder head, making it a normal four stroke like I have done. As the boss on my cylinder is unmachined, it has clearly never had flame ignition.
Title: Re: Mystery engine
Post by: RayW on December 21, 2021, 10:15:48 AM
In cleaning up the finned cylinder, I have uncovered a mystery and I am hoping that the MEM brains will come up with some possible explanations

Around the circumference above the first fin, at the cylinder head end, and in line with each threaded hole, I found what appeared to be the end of a small diagonal pin.

When cleaning up between the first two fins, I found a lot of some sort of red lead type filler, for which I could see no reason at first. Having dug out more of this filler, I discovered that each of the diagonal pins goes into a small vertical hole between the fins. These holes are obviously only shallow as there is no evidence of penetration into the cylinder bore. Presumably, the filler was to prevent corrosion breaking through into the bore when water cooling was used, as the holes must have thinned the bore wall considerably at these points.

So far I have been unable to come up with any explanation for the pins, so I will be interested to hear the thoughts of other members.
Title: Re: Mystery engine
Post by: Twizseven on December 21, 2021, 11:03:03 AM
Ray,
Do they go in deep enough that the inner edge would have reached the lower end of the stud.  i.e. could they have locked the stud in some way.

My other thought if they reached the stud hole is that they could have let the hole breathe as the stud was screwed in.  Sort of air release.

Silly ideas, but you did ask.

Looking closer at the second picture where the pin can be seen between the two fins, that hole looks round, was it drilled in from the side of the cylinder for some reason and the diagonal pin was used to hide it.

Colin
Title: Re: Mystery engine
Post by: Jasonb on December 21, 2021, 12:15:56 PM
I too would have thought some means of stopping the studs coming loose, maybe the threads in teh heads became worn or got damaged at some time and would not hold very well?
Title: Re: Mystery engine
Post by: RayW on December 21, 2021, 12:55:53 PM
Locking the studs was my initial thought. Thinking about it further, I wonder if, when originally built as an air cooled engine, the studs holes were drilled right through into the gap between the first two fins. Then, when converted to water cooling, the lower part of each hole was plugged, pinned, and sealed with the red sealant to avoid leakage. Looking closely, I think I can just about detect the pins visible in the very bottom of the current holes.
Quite why the horizontal holes where the bottom of the pins locate are there is still a mystery, unless it was as a visible guide as to how deep to drill the pin holes.
I have now filled the holes between the fins with JB Weld but will leave the outer ends showing as part of the engine history.
Title: Re: Mystery engine
Post by: RayW on December 23, 2021, 02:11:17 PM
What a difference a bit of JB Weld and a coat of Very High Temperature paint makes.
Title: Re: Mystery engine
Post by: Roger B on December 23, 2021, 08:31:48 PM
 :ThumbsUp:  :ThumbsUp:  :wine1:
Title: Re: Mystery engine
Post by: RayW on December 24, 2021, 04:31:26 PM
Now re-assembled in air cooled format and definitely looking better than with the old copper water jacket.

Title: Re: Mystery engine
Post by: Alyn Foundry on December 24, 2021, 04:34:54 PM
Blimey Ray….

That’s looking great.   :cheers:

Merry Christmas.
Title: Re: Mystery engine
Post by: RayW on December 24, 2021, 04:38:59 PM
Thanks Graham.
Happy Christmas to you and to all other members and here's hoping for a happy and healthy New Year.

Title: Re: Mystery engine
Post by: RayW on December 28, 2021, 02:38:37 PM
Finally got the engine to run really well, to the point that it would even start by hand, rather than having to use the electric drill to spin it over. All the settings, ie gas pressure, needle valve setting and ignition timing are super critical at the moment, so some more fine tuning is required, but at least it starts and keeps going now!
I have found that the air valve on top of the cylinder needs to hang slightly open normally, being  closed by pressure in the cylinder on the compression stroke.

https://www.youtube.com/watch?v=fbL2bfyWV90
Title: Re: Mystery engine
Post by: Jasonb on December 28, 2021, 03:05:48 PM
It's quite lively now you have it running well.
Title: Re: Mystery engine
Post by: Roger B on December 28, 2021, 04:42:34 PM
Excellent  :praise2:  :praise2:  :wine1:
Title: Re: Mystery engine
Post by: Admiral_dk on December 28, 2021, 10:08:27 PM
It is really taking off - so even if you are not totally happy about it yet - I will say that this is a major milestone you have passed with it  :cheers:

Per
Title: Re: Mystery engine
Post by: Alyn Foundry on December 29, 2021, 11:50:13 AM
She’s running a treat Ray.

Now you’ve found the “ sweet spot “ perhaps it’s time to try the hot tube again?

Cheers Graham.
Title: Re: Mystery engine
Post by: RayW on December 29, 2021, 01:53:20 PM
Had it running most of the morning today. Lost a bit of compression when it blew the gasket between the two halves of the valve chest but still ran. I did make up an adaptor and fitted the hot tube that came with the engine, but couldn't even get the tube hot. I have a stainless tube that I made that screws in place of the spark plug, so might try that.
Title: Re: Mystery engine
Post by: Admiral_dk on December 29, 2021, 07:33:24 PM
I do not have much experience running small scale IC engines in this regard - but I can tell you that on full size ones you can often destroy the gasket surface quickly, if you run it for a while with a broken gasket ....
But I guess that pressure and temperature has a lot to do with it - so a coasting engine, might not do any damage  :noidea:

Do you think it was the gasket material, surfaces or the pressure holding them together that was the reason ...?

Per
Title: Re: Mystery engine
Post by: RayW on December 30, 2021, 01:24:43 PM
Hello Per,
The two mating surfaces are machined and grooved so should seal OK with a good gasket. The one I used originally was a bit too thin.
I replaced the thin gasket with some silicone gasket sealant, which held for a while, but I was too impatient and ran the engine before the sealant had had time to cure properly. I will try that again, but if that fails, I will replace with a thicker gasket.
Title: Re: Mystery engine
Post by: RayW on December 31, 2021, 12:20:17 PM
Had an unsuccessful try with the hot tube this morning, but couldn't get the engine to fire. Had a couple of minor gas leaks around the inlet air inlet valve on top of the cylinder, and around the gas inlet valve stem, both of which ignited. Reverted to spark ignition and had a very successful mornings running until the gasket between the two halves of the valve chest blew (again!!).
Up to that point compression was really good with strong bounce back and good steady running.

The valve chest effectively forms part of the combustion chamber and gets very hot, as shown by the discolouration in the attached photo. The gasket I had fitted this time was thicker than the previous one, and fitted with a smear of silicone gasket sealant on either side.The two halves of the valve chest are held together with three small round headed screws (similar in size to 4BA).

Due to the proximity of the screw holes to the outside edge, there are several places where a fibre or paper gasket will inevitably be weak. I am wondering whether a thin annealed copper gasket would solve the problem.


 
Title: Re: Mystery engine
Post by: Admiral_dk on December 31, 2021, 12:46:44 PM
The three holes kind of ruins the idea of how the groove should keep it 'tight' .... but I wonder if a lapping of the surfaces will help / be necessary - if you either drop the gasket or use a metal one (here aluminium or copper comes to mind) ....

If you try a metal one, it must be thin and soft (heat treated copper - I'm not sure about how to make the aluminium one).

I'm sure that you're right about the heat + pressure destroys normal gasket material.

Best wishes

Per
Title: Re: Mystery engine
Post by: Dan Rowe on December 31, 2021, 01:39:40 PM
I think a full copper gasket should work. The only holes needed are the three bolt holes and the key hole section. It looks like the key hole tab is the weak part.

We used hundreds of copper gaskets on the diesel engines I worked on including head gaskets.

Cheers Dan
Title: Re: Mystery engine
Post by: RayW on January 01, 2022, 01:34:08 PM
Did away with the gasket altogether and achieved a satisfactory seal by lapping both faces.
Title: Re: Mystery engine
Post by: Admiral_dk on January 01, 2022, 08:35:23 PM
Great - so now it runs without any problems ?
Title: Re: Mystery engine
Post by: RayW on January 01, 2022, 09:37:46 PM
Running nicely now thanks Per. Just need to play around with valve timings, etc to get it running a bit slower if possible. Next job is to paint it in a suitable "old" colour, perhaps a matt dull red? The Mid Brunswick Green and black that the body and base are painted now are really not in keeping with the age of the engine. It seems that many of the early Schoenner engines, after which this is modelled, were finished in shades of dull red or brown.
Title: Re: Mystery engine
Post by: RayW on January 21, 2022, 03:28:30 PM
Fitted a slightly larger section Viton O Ring to improve compression. It was a bit too tight to start with, but soon wore down to a nice fit. I started to have problems with starting and when I tried the spark plug outside the engine I was getting a good strong spark at the plug from the trembler coil at low revs, but completely losing the spark once speed increased. All electrical contacts appeared to be good, so came to the conclusion that the coil must be breaking down.
I purchased and fitted a Minimag MCL-1 electronic ignition kit and got a spark at all speeds, but still very weak. After further investigation, I found that the spring brass strip which makes contact with the rotating disk on the crankshaft, was vibrating and only making the lightest of contact, insufficient to give a good spark at the plug. With a bit of bending to give a tighter contact, the engine burst into life, so I now suspect the the Model T Ford trembler coil was not at fault after all. At least it will come in useful on some future engine.
Title: Re: Mystery engine
Post by: Admiral_dk on January 21, 2022, 07:37:54 PM
Oh yes - it's often the small details that makes the difference  :)

Great that you have a satisfactory result  :cheers:

Per
SimplePortal 2.3.5 © 2008-2012, SimplePortal