Felgiebel 16,6

[F-DS]

I used a needle and a nozzle from the MVVS 2.5 engine for the carburetor, as both components have quite the same parameters and as they were available. We will see if the cross-section of the nozzle nozzle hole will suffice for the engine, historically a petrol engine with a capacity of less than 17 cc could have similar consumption as a modern glow engine with a capacity of 2.5 cc.

I made two square washers with a semicircular recess for the nozzle nozzle.

 

[F-DS]

I made the circuit breaker according to the original plans, it is just built upside down, as well as the exhaust and overflow channel of the engine. The main body is soldered with silver. The contact on the spring is made of silver, the second contact is an ordinary M3 screw without any modification, in time I will probably either use brass or cover the existing screw with silver. The screw tightening the breaker sleeve is temporary.

 

[Peter Twissell]

That clip will definitely rotate in the groove and unless your engine is only going to run at low rpm, the risk of it coming away is high.
How far can the conrod move backwards before it contacts the inside of the piston?
It is normal in model 2 strokes for the backplate to limit conrod movement. Heavily used engines which I have stripped show very little wear in that area, so there is clearly not much force there.
Perhaps make a new cover or attach a disc to your existing cover.

 

[F-DS]

I started the production of the last component of my engine - high voltage coils. I wound the primary winding manually, I made a simple electric winder with a counter for the secondary winding. I have already wound 2 layers of secondary winding of 500 turns and it works as expected. The primary winding has a diameter of 0.5 mm (a total of 130 turns), the secondary 0.1 mm (30 x 500 turns). I insulate the winding layers with "Modelspan" paper.

 

[F-DS]

I finished the high-voltage reel, the photos show paper insulation, temporarily secured with a fishing line.

 

[F-DS]

The coil is complete, the ignition is operational and two attempts have been made to start the engine. For the first time, the engine experienced only isolated inflammations, the engine was unable to run due to an ignition failure. I made the second attempt with the "Henry" ignition. I managed to keep the engine running for 7s, that's a success. Now I have to look for a few mistakes and the engine will be one step further to the moment when it will run reliably. First of all, I have to increase the ignition current (2 alkaline monocells are not enough), then I have to increase the axial clearance of the crankshaft to 0.5-0.7 mm, instead of the current 0.3 mm. Finally, it is necessary to focus on better switching of the circuit breaker, as it is the source of the biggest problems.

 

[KenC]

Maybe I skipped over something, but I did not see anything about how you made your piston rings, which is quite a technical thing to do correctly. Or perhaps you built your engine to use some commercially available rings.
Ken

 

[F-DS]

Hello, I bought the rings, I write about it in my 5th post.

 

[KenC]

Thanks, my mistake. I guess that aged 80 I am allowed a few!
Buying rings was very wise, though I have always made my own following the Trimble method.
Ken

 

[F-DS]

What method of production do you mean by "the Trimble method"? Cutting a ring from a pipe?

 

[KenC]

George Trimble is/was a model engineer who wrote an article in one of the magazines, possibly "Strictly I C" about designing and making piston rings. It is fairly well known by experienced model engine builders. Too difficult by far to summarise so if really interested maybe a Google search might find a reference to it. Apologies but I no longer have a copy.
Ken

 

[F-DS]

Thank you for the explanation.

 

[F-DS]

When I saw during the tests how the engine can kick after being swallowed with fuel, I began to wonder what would happen if the bolts holding the cylinder to the crankcase loosened during operation or a similar "kick", or rather tore out of the crankcase, because it holds only about 5mm in aluminum and the threads are not perfect. So I decided to partially disassemble the engine again and screw it firmly into the crankcase and glue the stitches to which the cylinder will be attached. This will better adapt the engine to future disassembly. Also, thanks to this modification, I may forgive myself for the future laborious repair of torn threads.

 

[F-DS]

Newly made connecting rods with threads (stiffs), with which I attach the cylinder to the crankcase. I also already have brass high nuts ready. All I have to do is glue the grafts to the screws and I can fold the engine.

In the end, I had to make stints and nuts in 6 pieces, because I always didn't succeed in 2.


The last picture shows the grafts with the screws originally used.

 

[F-DS]

And here it is, today I started my Felgiebel for the first time.

 

[F-DS]

It was around 8 ° C, Natural 95 fuel and M2T oil in a ratio of 1: 4. I finally used an electronic ignition, with an interrupter. I plan to release the high voltage coil in the future. I started the engine about 15 times today, each time for about 30 seconds, then it warmed up and started to tighten. Maybe he'll let it go by running in, but even so, I fulfilled my dream of making a functional internal combustion engine at the age of 17. Maybe I was unnecessarily complicated, but I got to the end and that's the main thing.

 

[rweber]

You rellay used a mixture 1:4? I guess you mean 4% Oil

And if it gets tight when it warms up: Check piston-zylinder clearance!

 

[rweber]

I forgot: Congratulations for your running engine!

 

[F-DS]

Indeed, the ratio of oil and gasoline is 1: 4, for the original, the run-in was 1: 3. Thank you for your congratulations.

 

[F-DS]

I know that the piston is too tight, I was already afraid of tightening during production. But I prefer tighter and then grinding than looser and making a new one.