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Cox .01 /.02 /.05 /.09 /.15 Speed Planes  - Page 29 Babe_b10
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Cox .01 /.02 /.05 /.09 /.15 Speed Planes  - Page 29 Empty

Cox .01 /.02 /.05 /.09 /.15 Speed Planes

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Happy Re: Cox .01 /.02 /.05 /.09 /.15 Speed Planes

Post  balogh on Wed Oct 14, 2020 6:04 am

Thanks, Brad,

yes, exactly as you advised, I chamfered the header entry.

Why do we use 140 for the timing here, instead of the 160 used in the earlier formula? Even if SPI, the exhaust timing remains the same as in a non-SPI cylinder??

I also noted, that the Kyosho muffler may not allow the cylinder thread to fully bottom out in the crankcase, and it may slightly reduce the compression ratio to some extent, albeit not so much that would justify the limping of the engine well below 20k. I did not want to force the cylinder to fully screw in against the Kyosho muffler, but will see if repeated spanning of the cylinder will cause the aluminum header to yield/wear some and the components will finally settle..
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Happy Re: Cox .01 /.02 /.05 /.09 /.15 Speed Planes

Post  1/2A Nut on Wed Oct 14, 2020 6:13 am

That was an example using another engine, you must know timing per engine type.
TD timing is typically 140 degrees, but can vary between 140 - 145

Per post:
1/2A Nut on Sun Oct 04, 2020 10:41 pm

Formula to sort out setting up the pipe example:
- 1675(wave speed) x 160(timing) ÷ 8.5 (pipe length) = 31.53K rpm

Constant:
1675(wave speed) x ___(timing) ÷ ____ (pipe length) = ____rpm

For the cylinder mark location when it seats without the manifold on.
Can very carefully flat sand the manifold - adjusted / small amounts or
you risk loss of a tight seal. Set the manifold tight just before the marked location.
Or allow it to wear in Kyosho did the right thing
to have it a bit off to insure all engines seal the manifold.

Forget your poor results with the wrong prop.

Do you have a 4x4 / 4.2x4 / 4.4x3 / 4.6x3 to properly test the pipe on the bench?

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Happy Re: Cox .01 /.02 /.05 /.09 /.15 Speed Planes

Post  1/2A Nut on Wed Oct 14, 2020 11:29 pm

How many head shims are you using?
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Happy Re: Cox .01 /.02 /.05 /.09 /.15 Speed Planes

Post  balogh on Thu Oct 15, 2020 1:02 am

Thanks Brad. Will check if I have the exact same props hou mentioned. I use 1 shim only but suspect that the cylinder does not bottom out. However I will look at the exact position through the cylinder top before and after the Kyosho is added.
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Happy Re: Cox .01 /.02 /.05 /.09 /.15 Speed Planes

Post  1/2A Nut on Thu Oct 15, 2020 1:11 am

Yes good to know just where the cylinder is at, 1 shim is good to make up for the variance.
With the plug off you can check the deck height with one shim.
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