Author Topic: Mystery engine  (Read 1470 times)

Offline Jasonb

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Re: Mystery engine
« Reply #15 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

Offline Alyn Foundry

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Re: Mystery engine
« Reply #16 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.

Online RayW

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Re: Mystery engine
« Reply #17 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.

Ray

Online RayW

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Re: Mystery engine
« Reply #18 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.
« Last Edit: September 29, 2020, 06:00:29 PM by RayW »
Ray

Offline Alyn Foundry

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Re: Mystery engine
« Reply #19 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.

Online RayW

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Re: Mystery engine
« Reply #20 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.
Ray

Online RayW

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Re: Mystery engine
« Reply #21 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.
Ray