# Small Gas Engine



## mhirst121 (Jun 30, 2012)

Hello all, while attending the 1000 engine rally here in the UK I came across these castings for a small gas engine. The large parts had been machined and a few items were included with the castings. It is always a risk buying castings that have been machined as to whether they are correct or not, luckily these measure up fine to the drawings. 
The engine is not a model but a full size engine. The bore is 61mm and the stroke is 80mm. The flywheel is around 14" in diameter and 2" across the face.
Although it is not a model, It is a Klein gas motor of German manufacture, I thought some of you would like to follow my trials and tribulations in a build log for it.
I will be ran on propane and have hot tube ignition, it has sideshaft driven cams that operate the valves. I may also fit a CDI ignition unit and spark plug so that the engine can be run outside if it is windy.
Let me know if you think a build log would be of use to anyone.
A few pics of the castings below, the vernier in front of them is 6" and should give some idea of the physical size of the engine.
Cheers,
MartinH


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## vcutajar (Jun 30, 2012)

Hi Martin

I have pulled a chair and will follow you on your journey. Hope you do not have any missing castings.

Vince


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## mhirst121 (Jun 30, 2012)

Vince what you see in the pictures is all I got, the sideshaft perch brackets and the mains caps will have to be machined or fabricated. Shouldn`t be too much of a problem, the mains caps will be a bit more work as one half is already machined, will have to match the caps up to them.

MartinH


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## rebush (Jun 30, 2012)

Martin: Can't wait to see where this leads. I'm sure it will be interesting. Roger


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## Don1966 (Jun 30, 2012)

Any engine built is interesting to me, I will follow you on your venture it looks like a real educational venture to me.

Don


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## Jasonb (Jul 1, 2012)

I'll be watching, always a softie for a gas engine.

It's a pity there is not more metal on the lower bearing housings as you could have made the tops and then bored oversize and bearings to suit, maybe there is still room for a light skim?

J


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## mhirst121 (Jul 2, 2012)

Right then, let the fun begin. I like to work from castings, don`t know why I just do, so with this in mind I decided to make the parts I felt should have been in a complete set of castings. With this in mind I thought I would start with the sideshaft perch brackets.

Blocks of steel for brackets





Blocks machined square and to required size





Marked out





Excess cut out on the bandsaw





Step milled to size





Recess for cap machined





Cap block machined to fit main part





Drilled and tapped for screws





Ready for the lathe





Centred in lathe ready to cut first face and bore





First face done and bored to size





cap screw faces machined





Finished cap





Bracket mounting holes drilled and marked out and cut to lines of finished size





Finished brackets





And test fit to the engine











I will tidy them up a little more with a file to make them look a little more like castings. Well thats a start anyway.

Cheers,
MartinH


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## Herbiev (Jul 2, 2012)

Thanks for sharing Martin. Looking forward to next instalment :bow:


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## idahoan (Jul 2, 2012)

Great stuff Martin,

Please keep posting your progress on this neat little engine.
How will it be fired? Hot Tube maybe?

Dave


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## idahoan (Jul 2, 2012)

Oops, Sorry; I went back and read your original post where you said that it would be hot tube ???

Dave


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## mhirst121 (Sep 9, 2012)

Well here we are again, sorry it`s been so long since the last post on the progress of this engine but sadly my father died and I did not feel like playing computer for a while. 
Anyway I have made a little progress on the engine but unfortunately did not take as many pics as you would like, so I have taken some of the parts that are done for now and promise to try harder in future on the pics front.

Cheers 
MartinH

This is the liner (61mm bore), I made it from a piece of solid EN24 bar I had lying around, should be more than tough enough for the job. I also added `o` rings to either end where it fits in the casting, just in case it has to be removed in the future.






Piston and liner






Liner installed in block






The finished crankshaft, I may fit balance weights at a later date, that is why I have not shaped the ends of the webs.






The bearing caps






The valve cages, these were blocks bored out then caps made and silver soldered on to them. When I make the valves I will cut the seats and bore the holes for the valve stems to get everything at the same angle and in line.






Thats all for now


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## vcutajar (Sep 9, 2012)

Sorry to hear of your loss.

Vince


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## robcas631 (Sep 9, 2012)

I am very sorry to hear that your father passed on. I simply have no words....


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## mhirst121 (Sep 16, 2012)

Well I managed to get a bit of me time the last few days and heres a few pictures of what I have been up to.

First I made up the big end bearing from a solid lump of 3" diameter phosphor bronze bar. I didn`t take any pictures as I was too busy concentrating on the job in hand so as not to mess up the rather expensive piece of bronze. Anyway heres the result with the taper turned rod. I did the rod between centres with the tailstock offset.






And one with the piston connected.






Next I moved on to the crank balance pieces. I made these bolt on type as this is what alot of the early engines used and also they can be removed if not required or need adjusting.
First cut parts from piece of 10mm plate on the bandsaw.






The radius was then cut on the rotary table.






The angle sides were then dressed and the pieces set up in the vice using the laser to find the centre point.






The slot for the crank web could then be cut.






The holes were then drilled and counterbored for the screws.






How they look on the crank.











A few other little jobs were cleared up these being the sideshaft bushes, which were just a straight forward lathe job. The gears were mounted with grub screws to hold them till the final timing is set up, then they will be pinned in place.
An overview of where it`s at now. 






Coming along nicely, well thats all for now, off on holidays for a week so will not be back in the shop for a while.

Cheers,
MartinH


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## Brian Thomas (Nov 20, 2012)

Very impressive! Looking forward to the next installment. I like working with castings far more that raw stock as well.


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## myrickman (Nov 29, 2012)

Martin, sorry to hear about your dad. Went through it a few years back; my condolences. You engine is a real cutie! It appears you are doing it proud in your restoration efforts. It takes a bit more time, but there is always the pride factor which last forever.  I'll stay tuned to your progress. MM


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