Upshur Fuel Mixer

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rickhann

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I just almost completed the Upshire Engine serialized in the Strictly I.C. Magazine Oct/Nov 2000. Finally got it to run today. It seemed to run o.k. on a full tank, but would suddenly stop until the fuel tank was filled again (fuel drop of maybe a 1/4 inch in the tank). It seems to be extremely sensitive to fuel elevation and the needle valve is almost closed. My question is does anyone have any experience running this engine using Jan Ridders "Vapor Carburetor"? It seems to me that would solve the fuel level dilemma.
any insight would be appreciated. Thanks Rick
 

minh-thanh

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Hi !
Yes, I made and used the same one with my engine, it's in the same condition as you said
And it seems that when most of the easy volatile fuel is exhausted, the engine becomes harder to run
But it's a carburetor where you don't have to worry about fuel flooding in the cylinders
 

werowance

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i know you are asking about vapor carbs but on my upshur vertical i used some modified plans of the chuck fellow carb that the user "Awake" drew up. it works great and doesnt give me any trouble on tank height. i do have my tank height on an adjustable rod but i dont have to move it and it will run a full tank out on this carb.


post 410 is where Awake kindly shared his redrawn version of the chuck fellows carb. its very easy to make. i think it would have been even easier than the upshur drawn version which i didnt even bother trying to make.

hope this helps out if you want to try to stick with a regular carb instead of a vapor carb
 

rickhann

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Thanks for the replies. I have built a carb that is close to the Upsjire design, but I mounted horizontally. My thinking was that it might draft better horizontally than vertically. I tried it out tonite and it ran continuously for 5 or 6 minutes. It was continuous, but a bit sporadic. Does the point gap affect the running, I have it timed to fire a couple degrees ATDC. The point gap is .030" as suggested by several builders. My Upshire article recommends .010" to .015". Does it make a difference? If so, why? I would think that if it fires at the right time the the gap would not really matter. Rick
 

awake

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I am no expert, but I would say a couple of degrees ATDC is too delayed for good running; Minh-Thanh's suggestion of 5-15° BTDC is a much better starting place. For higher RPM, you'd want to advance that more.

On the points gap, I don't know how much it actually matters, but I am used to seeing something more like .015" to .020"
 

rickhann

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Here is a video of my Upshur Engine. The points are set at .016" and it is timed at a smidgeon before top dead center. I discovered that earlier problems were because my mixer needle valve would not close enough and it was running too rich. Th engine was built entirely from bits and pieces with the exception of the flywheels (Martin Models, highly recommended!). O-ring on piston (about .005" compression). It is ungoverned, not hit and miss. The plans recommended securing the flywheels with grub screws. Not a good idea!! Not secure and difficult to change timing once grub screws are set. I decided to use tapered split bushings to secure the flywheels. A little bit of a pain to do, but is well worth it. Zero wobble and timing can easily be change without mucking up the crankshaft with grub screw indentations. my only concern now is that it does get HOT very quickly. I will fabricate a water hopper and add it. A bit more authentic. Rick
 

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rickhann

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maybe this will work
 

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  • MVI_1605.m4v.zip
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