raym/rupinow vert hit & miss

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Brian Rupnow

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They were in there mainly for set-up. I put an 0.063" pin in there to hold everything in correct alignment before I drilled the holes in the bracket and cylinder. The hole really doesn't have anything to do with the function of the engine.--Brian
 

el gringo

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upper bracket... kind of a tetchy part for me to make.


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in a vise on the mill

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in the vise on the mill... the vise turned 30degrees on the mill bed to pick up the angles
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in the rotary table on the mill

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please holler if any questions
Ray M
 

Brian Rupnow

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Good looking parts Ray. That bracket is a good example of something made for "pretty". It could have been a lot simpler, but it wouldn't have looked nearly as nice.---Brian
 

el gringo

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Good looking parts Ray. That bracket is a good example of something made for "pretty". It could have been a lot simpler, but it wouldn't have looked nearly as nice.---Brian
yes, truly a case where form doesn't follow function. I suppose the question of form and /or function must have come up often for a design engineer due to possible cost
implications.
One of my favorite examples of a 'form and function' design is my old Southbend 9 inch model 'a' lathe.
Ray M
 

Johno1958

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Your making some good progress Ray. I also when I get to it:rolleyes: am going to have a go at making the rings which I have never done .
I have been saving a little bit of cast iron I have left over from another job that I got from Germany for making some rings as it seems
a better quality than what I have sourced locally of ebay.
Cheers
John
 

Johno1958

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Good stuff. I'll be watching
John
 

el gringo

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Looks like I have ~ 4.72:1 Compression Ratio with >.032 gaskets @ top and bottom of cyl. Am wondering how that compares with the original?
Looks like I can increase to ~5.5:1 by using .010 and .016 thick gaskets top and bottom...Also wondering what would be minimum CR for this engine to run properly?:rolleyes:

Ray M
 

Brian Rupnow

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Ray--I used .031" thick gasket under the cylinder and under the cylinder head. Engine ran just fine with that. I am not sure what you mean by minimum CR. I don't know what CR is.---Brian
 

el gringo

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Sorry Brian, here is a definition...
https://en.wikipedia.org/wiki/Compression_ratio

Do you have a feel for what the compression ratio is on your engine, possibly in your design notes?, or by checking the distance from top of piston @ TDC to cylinder deck with your computer aided design criteria or direct measurement?
Can anyone suggest a low end Compression Ratio on this type of engine?
I am wondering if I have made a mistake in dimensions and should possibly re-make some parts before continuing... looks like I can increase the CR to ~5.5:1 by decreasing gasket thickness to .o12 if need be.
Thanks
Ray M
 

Brian Rupnow

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Ray--For this type of engine compression ratio only needs to be 3.5:1 up to 5:1 The higher the compression ratio is, the less chance the engine will have of restarting after a series of misses. I believe the compression ratio of my engine is 4.5:1.--Brian
 

el gringo

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Thank you Brian... looks like my 4.7:1 is in line with yours, I didn't need to create a cavity in the head because of the type of spark plug used. I might use a .010 gasket on top cyl in order to increase the CR to 5:1.
Raym
 

el gringo

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RINGS... continued


heating with acetylene torch without direct flame contact with the rings
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'bout the color of a robins breast
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cleaning up the rough edges prior to final fit in the cyl (.003" gap)
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after de-burr and cleanup
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installed on piston
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cyl wall after thirty minute test run-in using external motor power
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Ray M
 

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