Author Topic: Four cylinder scale engine  (Read 27297 times)

Offline Art K

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Re: Four cylinder scale engine
« Reply #75 on: November 19, 2017, 10:43:14 PM »
Thomas,
The whole works as a family photo is great.
Art
"The beautiful thing about learning is that no one can take it away from you" B.B. King

Offline 90LX_Notch

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Re: Four cylinder scale engine
« Reply #76 on: November 19, 2017, 10:58:46 PM »
Fantastic work Thomas.

-Bob
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http://www.youtube.com/user/Notch90usa/videos

Offline ThomasM

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Re: Four cylinder scale engine
« Reply #77 on: November 26, 2017, 05:34:09 PM »
Hello,

Last weekend i was able to make the flyweel and distributor.

I also worked on the the carburettor this weekend. Everytime i build a carburettor i believe that i will be the best carburettor ever. This did not happen until today. All the carbs i have build until now worked but everyone of them has its own weak point. This time i will try a two needle type carb. The problem with the air bleed type is at my understanding that the vaccuum becomes low at idle and therefore the vaporisation of fuel becomes difficult. I hope with a two needle type i can reach a more controlable and better vaporisation at low idle rpmīs.
I also had the idea to make the travel of the second needle adjustable more or less regardless from the opening of the throttle.
In the picture with the carburettor parts you can see a black square plate with only one hole in the upper right corner. Thias part is bolted to the carburettor square or at an angle. When the part is fixed to the carb square there wil be no travel of the second needle when the throttle is opened. Whe the part is bolted on the housing at an certain angle the travel of the throttle and therefore the needle valve in the throttle will be influenced.

Here are the pictures :

1. The distributor is made of a 3d-printed part with grooves for the copper wires. After i inserted the bended copper wires i filled the grooves with polyester resin. The lower section of the distributor is of a different type of plasic with a higher melting point and glued on. The linkage to the cylinder head is made of a piece of fuel tubing to get the best possible thermal insulation.
2. The carburettor body. The part is build from three pieces of brass and a turned piece of aluminium.
3. All the carburettor pieces. I didnt grind the needles for the needle valves myself because my wife has enough carburettor needle valves in stock....
4 + 5. The assembled carb. The spring on the outside will not be visible on the engine because it is on the backside. I dont know if i will make a throtle lever to operate the carb directly or if i will make some kind of linkage to operate it with a mini gas pedal mounted on the engine stand .
6 - 8. The carb mounted on the engine. The silicone sealings for the intake and exhaust manifold are also already in place. 4 brand new 1/4 x 32 spark plugs are in place.

The to do list becomes shorter....

Best regards,
Thomas

Offline Mcgyver

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Re: Four cylinder scale engine
« Reply #78 on: November 26, 2017, 06:42:41 PM »
very impressive!

Offline 90LX_Notch

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Re: Four cylinder scale engine
« Reply #79 on: November 27, 2017, 02:22:43 AM »
This really is some great work Thomas.

-Bob
Proud Member of MEM

My Engine Videos on YouTube-
http://www.youtube.com/user/Notch90usa/videos

Offline william johnson

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Re: Four cylinder scale engine
« Reply #80 on: November 27, 2017, 04:31:41 PM »
real nice would like to have one

Offline Roger B

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Re: Four cylinder scale engine
« Reply #81 on: November 29, 2017, 07:28:43 AM »
Excellent  :praise2: Carburetors are always fun  ::) I hope that your new variant is successful  :wine1:
Best regards

Roger

Offline ThomasM

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Re: Four cylinder scale engine
« Reply #82 on: December 23, 2017, 08:53:08 PM »
Hello everyone,

It has been a while since the last progress on the Model A engine. The last few weeks i started the engine a few times but the carburettor described in my last post performed not the way i hoped. Also i had to sort out a few problems with the distributor which caused heavy misfiring of the engine. This misfiring caused a damage of the crankshaft which i was able to fix.

It is to early to show the engine running because i only can do very short runs of it. There is no radiator and coolant in it and after 20 seconds the engine becomes unbelievable hot. Without a working cooling system it is simple not possible to make tests with different carburettor settings and setups.

I wonder if it is normal for side valve engines to become very hot in a very short time ? Maybe it is because of the flat shaped combustion chamber whith a large surface area which catches most of the heat of the combustion gasses ?

Anyway, a radiator is needed and this was my work today. It is my first day of my 2 weeks christmas vacation and i was very productive.

The radiator is build from copper and brass tubing soft soldered together. It is 135 mm wide and 150 mm high. The cooling fins are made from aluminium.

The pictures :

1 / 2. Drilling of the 32 cooling fins. The measurements are 135 mm x 19 mm x 2 mm. After drilling undersize i reamed the holes with a 6 mm reamer to get a tight fit on the vertical tubes for a god heat transition. The vertical cooling tubes are 6 mm outher and 5 mm inner diameter.

3. Two fins are attached to the vertical tubing before soldering the lower copper tube, the wather hose attachement and the two covers of the vertical coper tube together. After this the vertical brass tubes are perfect aligned and the cooling fins can be slided on.

4. More copper tubing for making the top of the radiator. The upper horizontal tubing is larger ( 20 mm diameter ) to create some kind of water reservoir.

5 / 6 . The finished radiator. I plan to 3d print a cover for it in the future which makes it look the same as the original model a radiator grill .

Merry Christmas !
Frohe weihnachten !

Thomas.



Offline b.lindsey

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Re: Four cylinder scale engine
« Reply #83 on: December 23, 2017, 09:13:30 PM »
Thomas, it looks good. Are the fins just a friction fit onto the tubes?

Bill

Offline ThomasM

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Re: Four cylinder scale engine
« Reply #84 on: December 23, 2017, 09:20:21 PM »
Hello Bill,

I used a little bit of loctide on them. I forgot to say.

Thomas

Offline ThomasM

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Model A engine - running video
« Reply #85 on: January 03, 2018, 04:10:19 PM »
Hello everyone !

After i had to sort out a few issues with the transistor ignition which killed tons of hall effect switches ( bad lead to engine block ) the engine is running. :cartwheel: You will see a video of it in my next post. The video is made with my smartfone so unfortunately the sound quality is not the best.

To make this build log complete i also post a few pictures of the machining of the parts to make the engine complete.

I have to admit that i was not able to stop the massive oil pumping as a consequence of not properly working oil control rings so i have to use 1:50 mix to run the engine. Maybe i will build a little two cylinder test engine in the future which is easy to dissasemble to have the possiblity to do a little reserch on oil control rings but i am happy with the " 1:50 solutuion " also.

The carburettor which is used is a simple one needle type without air bleed and was initially for temporary use but it works so well i think i will keep it. Of course it still needs a litte fine tuning. The idle could be a bit lower but i am close.

The cooling without wather pump is working very good. To my surprise no water pump is needed.

The pictures :

1 :  The water hose attachment. I usually planned to cast this little pats like most of the other parts too. But it was easier to solder them together from seperate parts.

2 + 3 :  The mounting for the radiator fan shaft is also a soldered part.

4 : The cover for the valve stem gallery. The oil line goes to the camshaft gears. I hope the oil wich is collected from the gears is pumped to the valves.

5 : The ignition wires are 0.5 mm copper wire. I have seen many pictures of the original model a engine with unisolated wires so i copied this.

6 : The cooling fan is made with the 3d printer. It is driven 1:1 by a rubber belt made from tire inner tube.

7 : The fuel tank is recessed in the wooden engine stand so i have made an opening to check the fuel level from the outside. There is a led light in the box behind the glass tank to make it easier to see.

Best regards,
Thomas

Offline ThomasM

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Model A engine - running video.
« Reply #86 on: January 03, 2018, 04:11:30 PM »
<iframe width="560" height="315" src="<a href="https://www.youtube.com/watch?v=YKuXZLDxWN0" target="_blank">http://www.youtube.com/watch?v=YKuXZLDxWN0</a> frameborder="0" gesture="media" allow="encrypted-media" allowfullscreen></iframe>

Offline mnay

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Re: Four cylinder scale engine
« Reply #87 on: January 03, 2018, 04:58:05 PM »
Beautiful work.
I love the sound of it.

Offline Roger B

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Re: Four cylinder scale engine
« Reply #88 on: January 03, 2018, 05:53:24 PM »
Excellent  :praise2:  :praise2: What are you using for fuel? The tin seems to suggest some form of cleaning fluid  :headscratch:
Best regards

Roger

Offline ThomasM

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Re: Four cylinder scale engine
« Reply #89 on: January 03, 2018, 06:08:16 PM »
Roger, actualy coleman fuel is chemically nothing more than catalytic gasoline. Here in germany coleman fuel is not available but we have
 " Reinigungsbenzin / cleaning petrol " for degreasing issues . This is the same stuff.

 

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