A gearbox for a little locomotive

[Admiral_dk]

First - Congratulations for your new Sound from the Loco / Engine - it has a certain realism to it 

i was assuming, from what i have read and understood, (model engines are far from my academic degrees!) that with a longer stroke, my engine will give its peak torque at lower rpm, nearer from the wished "put put put put" and not the usual screaming note.

This is one of those Urban Myths that are imposible to kill 
You got the same pressure and if it is applied to a bigger surface, you have more power, but multiplied to a shorter stroke => same Crank output - and Vice Versa ...!
The true difference can be the Fuel/Steam consumption .... (but also other factors are in play here).

Per             

[RReid]

The engine runs very well, and sounds great! Congratulations, Zephyrin!
The muffler must work quite well, it would be interesting to hear "with" vs "without".
edit - Sorry, I overlooked the prior video that does just that. A significant difference!

[Kim]

Very effective muffler!  And interesting experiments to measure the noise level. Thanks for sharing those with us. 

She runs really nicely and makes a great put-put sound!

Kim

[Zephyrin]

 thanks for the comments, much welcome !
yes I love the put put sound, at last i feel a progress in this direction...
I will not do this sound test again as the muffler becomes rapidly really hot, and I burn my fingers...

a well of science as always Per, thanks , great to have a clear view on so many topics, as my engine is not yet complete...

[Zephyrin]

After putting the fuel tank in its final place, above the engine crankcase, as in the original model, I can no longer see the connecting rod turning alas, but above all new carburettor problems occur. It is harder to get the idle right, and the engine drowns quickly when starting... I did a lot more testing, (and even get some pops with the butane torch !) and finally rebuilt a new carburettor, with smaller passages from a small zamac casting: 
This new carburettor seems better, starting up is a lot easier... explosions from the first launches, and air fuel adjustments are possible very early on. The fuel inlet line is also more direct, with the fuel intake opposite the needle, well separated from the heat of the exhaust; I watch it running  with pleasure...
<a href="https://www.youtube.com/watch?v=mG7R_7boSOs" target="_blank">http://www.youtube.com/watch?v=mG7R_7boSOs</a>

[MJM460]

Well Done Zephyrin, a great result for all your work.  Good to see it running so well. 

Now for the track?

MJM460

[cnr6400]

    Great job!

[Vixen]

Well Done Zephyrin,

I bet you are 'chuffed' with the result.

Mike

[Kim]

Very nice, Zephyrin! 

Kim

[RReid]

Runs very well, and that is really a remarkable bit of packaging!

[Roger B]

Excellent    You must be happy with that 

Flexible carburation is a complicated subject which is one of the reasons I ended up working on fuel injection although I think at that cylinder size it would be beyond my skills 

[Admiral_dk]

Even better now - impressive 

Waiting to see it back on track pulling a wagon or two     

Per

[Zephyrin]

thanks for the comments !

Yes, the next step is on the track at the club...
I'm doing a small wagon to carry the ignition box and the battery, as the loco is already too tightly crowded.
I also have to make the bonnet, probably only for the shelf, as the temperature inside while running would certainly be too high ...

[Zephyrin]

Here's the first test of my little locomotive on the club track...
A successful test, I'm happy to say! The engine and transmission worked well together.

I finally had to build a small wagon, as I couldn't find anywhere else to put the ignition box. It was merely 4 wheels and 4 axle boxes cast in Zinc alloy, bolted on a brazed steel frame.

although the idling engine does drive the loco at a realistic very low speed, I don't really like this snail's pace, I prefer to step on the throttle and watch my loco move along the track at a faster speed...
The drawback is that the little 4-stroke gets very hot at the end of the run, when the 10 ml of petrol is over, about 10 minutes, the cooling water is almost boiling.

<a href="https://www.youtube.com/watch?v=8H-LTSykAkM" target="_blank">http://www.youtube.com/watch?v=8H-LTSykAkM</a>

[cnr6400]