Stevens's Model Dockyard- Marine engine

[Sanjay F]

The next little project is going to be a return to get this little marine engine working. I've had this for quite a while and although it may look like its done, it's not. I bought this not knowing what it was until last month when I got a raggedy original copy of a Stevens's Model Dockyard catalogue from 1930 - 1931 and stumbled upon what I have here. I'm fairly certain its either one of the Direct Acting Marine Screw or Marine engines as its fairly unusual in design?

When I first got this I made the metal base and wooden plinth as it doesn't stand up on its own!  . I have so far been unable to get the timing and port openings correct to get it to run; there is no way of visually seeing the ports as you adjust things which is a major disadvantage, but maybe someone out there has one of these and holds the secret?

I really like this little engine and it'll be a shame for it to sit on the shelf without being operational .......... let the dismantling begin......I post lots of photos so you can see the internals

[Sanjay F]

Couple of videos:

https://www.youtube.com/shorts/hPNvkkncgcA

https://www.youtube.com/shorts/hbhmYZMgry4

[Sanjay F]

More pictures....

and herein is the problem, the valve faces towards me so when the chest is put back on you cannot see how the valve is moving & opening/closing the ports. Secondly the only adjustment for the port distances is a minute amount of thread on the top part of the eccentric and its VERY delicate - I don't want to strip that thread! The eccentric is adjusted by the screw on the sheave and means dismantling the strap to get to it ......... lot's of little awkard 'features' 

[Sanjay F]

I place the port face so I could see it and turned it over to make sure the valve was behaving itself and not hitting anything, looks ok, but its not very scientific 

https://www.youtube.com/shorts/gvrrVXlpKYo

[Jasonb]

I don't bother looking at the valve when setting the timing.

First with the cylinder removed check the valve is moving to expose equal amounts of port top and bottom by holding teh cylinder port face at right angles to the valve chest. It may help to put a piece of masking tape down the cylinder and use a fine pencil to mark the port positions to you can better judge valve position.

Then you can set the timing based on the high point of the eccentric. A good rule of thumb is to have the high point of the eccentric leading the crank pin by 90deg plus another 30 degrees. So while the crank is upper most at 12 o'clock you want the high point of the eccentric at either 4 or 8 o'clock depending on which direction you wnat the engine to run.

I'd say is is a No248 which was also in my 1919 catalogue.

[vtsteam]

I love that engine! 

[Sanjay F]

I don't bother looking at the valve when setting the timing.

First with the cylinder removed check the valve is moving to expose equal amounts of port top and bottom by holding teh cylinder port face at right angles to the valve chest. It may help to put a piece of masking tape down the cylinder and use a fine pencil to mark the port positions to you can better judge valve position.

Then you can set the timing based on the high point of the eccentric. A good rule of thumb is to have the high point of the eccentric leading the crank pin by 90deg plus another 30 degrees. So while the crank is upper most at 12 o'clock you want the high point of the eccentric at either 4 or 8 o'clock depending on which direction you wnat the engine to run.

I'd say is is a No248 which was also in my 1919 catalogue.

I have marked TDC on the flywheel with an arrow and the eccentric is currently also set at 12 o'clock with the shortest distance which is clearly incorrect as it needs to be the 'high point' as you call it, at 90 deg plus 30. I think the high point is the arrow I've marked in the photo? Basically 180 degs from where its currently positioned?

[Jasonb]

That's it at the bottom as marked on the photo, no real need to mark the flywheel when you can just look at the crank pin at the other end

[Jasonb]

I love that engine! 

Yes, almost tempted to add it to my Future projects list. Ideal candidate for a bit more 3D printed metal. But then I would have to do the oscillating version too

Sanjay what size engine is it, from the photos I would assume the smallest?

[Sanjay F]

Yes, I think it's the size 1, 3.5" tall

I have tried from 3 o'clock to 5 o'clock incrementally and the video shows 4 o'clock, she's trying to go but if you listen there is the sound of the exhaust throughout. This is happening in all positions, so I think another dismantle and checking the ports using your masking tape method may be called for.

The pin in the scotch yoke is a pain, its either too tight and jamming things up or too loose and striking the guide. I may use  a bit of super glue temporarily on the lock nut to hold it in the correct position

https://www.youtube.com/shorts/yuZof_bfMls

[Jasonb]

If you can hear air all the time then the valve may be sticking on the nut or rod and not seating on the port face. Make sure it is free but not sloppy. Sometimes holding the engine with the cylinder port face upwards and giving the engine a tap when the air is on will be enough to get the valve to seat.

[Sanjay F]

Oh what a beautiful sound!

I reset the eccentric back to 4 o'clock, tightened up the piston gland, super-glued the crank pin lock nut into position, turned up the compressor and hey presto ........... she's running 

I'm so pleased, it's taken all day, but so worth it, I love seeing these little engines run especially as she's be sitting idle since my last attempt.........thanks Jason 

https://www.youtube.com/shorts/cmpvVEccN-8

I'm now thumbing through the rest of the old catalogue looking at some of the other old beauties which they made! 

[PaulR]

Very nice and sounds good too. 

[vtsteam]

Great!

[Chipswitheverything]

No doubt about how well this little engine runs after your playing around to get it going after very many years. The design is rather neatly done, surprising just how simple and compact a purely functional model steam engine can be.  The Dockyard catalogue was a nice find too.  Dave