Author Topic: Please help, I am building my very first engine.  (Read 2477 times)

Offline alm56

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Please help, I am building my very first engine.
« on: December 12, 2016, 04:01:27 AM »
Hi friends, I am in the process of building my very first engine, A Flame Licker Engine, It was a 20cc 2 stroke Weed eater engine, I am making it into a open crankcase and it will have a walking beam overhead to run the slide valve that will be on the cylinder head, My question is, The existing spark plug hole in the head is 12.75 mm, That's all most 1/2" Is this the correct size for my Gas/Flame hole, And should I leave it round or make it square or some other shape ?
34.56 mm Bore
25.01 mm stroke
1.34252" Bore
0.98819" stoke
Thank you guy's so much...
« Last Edit: December 12, 2016, 04:21:27 AM by alm56 »
ALM56

Offline b.lindsey

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Re: Please help, I am building my very first engine.
« Reply #1 on: December 12, 2016, 04:13:33 AM »
Allen, a picture of the head would help a lot. The opening size should be OK as long as you can close it off and seal it well. The flame size will have some impact too though. The most critical things about vacuum engines are the piston/cylinder fit and as little friction or binding anywhere in the engine as possible.

Bill

Offline alm56

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Re: Please help, I am building my very first engine.
« Reply #2 on: December 12, 2016, 04:22:01 AM »
Thank you, I am very happy I found this great site, I do have a problem already, I can't see how to ad pictures ? I do see a small button above that said insert image, But when I click on it I just get this
ALM56

Offline crueby

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Re: Please help, I am building my very first engine.
« Reply #3 on: December 12, 2016, 02:29:46 AM »
Easy way is to click below the text box where it says Attachments and other options. Then click the choose file button to pick your jpeg file. Best to keep the pics small, like 800x800 pixels.

Offline Brendon M

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Re: Please help, I am building my very first engine.
« Reply #4 on: December 12, 2016, 07:24:21 AM »
Hello alm56, see the Suggestions and Forum Help section for info on the three different ways you can host images (google, MS OneDrive and attaching directly as suggested by crueby)
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Offline yogi

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Re: Please help, I am building my very first engine.
« Reply #5 on: December 12, 2016, 09:17:29 AM »
The hole size seems big enough to me. Like Bill said, friction is your enemy. Flame lickers have so very little power, even the smallest amount of binding will prevent the engine from running.
Good luck with your project, and keep us posted.

Offline BillTodd

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Re: Please help, I am building my very first engine.
« Reply #6 on: December 12, 2016, 12:40:50 PM »
Flame licker's rely on a phase change (Plasma condensing into a hot gas with a consequent reduction in volume ). The challenge is to get enough plasma (flame) into the cylinder before it cools and rapidly condenses.

The plasma has negligible thermal conduction, but almost no thermal mass, it loses heat principally by radiation , so polishing all the internal surfaces to a mirror finish will help to keep the energetic photons bouncing around and back into the plasma, keeping it hot longer.

The timing valve has to allow the hot gas out of the cylinder for the next induction stroke and, ideally, direct the gas away from the flame.
Bill
wy omnibus Latinis taurus stercore?

Offline Ian S C

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Re: Please help, I am building my very first engine.
« Reply #7 on: December 12, 2016, 01:32:45 PM »
One thing you must do is eliminate as much friction as you can.  The original piston with it's rings is not really suitable as the ring press tightly on the cylinder bore. The piston/cylinder in these motors run with very little lubrication, and the best is to make a new piston, best made of cast iron, this should be lapped to fit the cylinder with no rings. The piston is the right size when it will slide through the cylinder under its own weight, but virtually stop if the end of the cylinder is blocked.
I don't know the cylinder you are using, you may have a problem if it has transfer ports down near bottom dead center.
Ian S C
One of my motors with a Prony Brake to apply a load to test the power of the motor.
« Last Edit: December 12, 2016, 02:01:41 PM by Ian S C »

Offline b.lindsey

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Re: Please help, I am building my very first engine.
« Reply #8 on: December 12, 2016, 02:28:45 PM »
Allen, there is also a tutorial at the very top of the Suggestions and Forum Help section that may be helpful to you.

Bill

Offline alm56

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Re: Please help, I am building my very first engine.
« Reply #9 on: December 12, 2016, 10:10:40 PM »
Bill, Thank you so much for taking the time to help me, I truly appreciate it, By the way, The cyl. does have BIG Transfer ports, I filled and sealed Them, Intake port and exhaust port (All) with JB Weld Metal Stick
« Last Edit: December 12, 2016, 08:13:38 PM by Jo »
ALM56