Upshur 4 Stroke Single

ironman · Feb 9, 2015

Who has built this engine? I think someone here did one with a solid block instead of the built up housing.

I started the built up one using Strictly IC issues 63, 64, 65 and 66 a few years ago but now I can't find my issues. They are here somewhere.:wall:

I need camshaft and cam specs mainly for now. Help....

ironman · Feb 9, 2015

Well disregard my friends. I found my books along with all my CAD Drawings on a thumb drive. All is well.

rklopp · Feb 10, 2015

I wonder if the Upshur single cam is same as for his twin. I am building six each of the Upshur Twin. I was not happy with the cam profile or timing, so I redesigned the camshafts based on harmonic motion and made the timing same as the old English Wyvern design. I kept the lift the same. To get harmonic motion, the flanks need to be circular arcs, rather than flat as in the original design. In addition, I made the tappet faces larger to avoid digging the edges into the cam running faces. I have not run the engines yet, but I am getting close. I am finishing up the valve springs. Then I need to do fuel and ignition systems.

tornitore45 · Feb 12, 2015

I built the Upshur twin as documented in the Model Engine Builder Magazine.
In that incarnation the cams have curved flanks.

The twin engine runs well but the carburetion is fairly touchy.

rklopp · Feb 12, 2015

tornitore45 said:
The twin engine runs well but the carburetion is fairly touchy.

That's why I am going to use somebody else's carburetor design when I get to that part.

tornitore45 · Feb 14, 2015

That's why I am going to use somebody else's carburetor design when I get to that part.

Could you post more info on the alternate carburetor?

Thanks

rklopp · Feb 14, 2015

I don't have one in mind yet, but will start by googling Rupnow and Fellows designs.

Upshur 4 Stroke Single

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