Author Topic: Outside the box (almost)  (Read 538 times)

Offline rick41

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Outside the box (almost)
« on: December 11, 2021, 08:52:16 PM »
I am sitting here in FL with my shop 1000 mises away, so I have time to think.  I have built several hit and miss engines, and they all, run!  Galloway, Lil Brother, & Upshur.  They all are sensitive to the difference in elevation between the fuel elevation and the carburetor/mixer elevation. I have been thinking about how to ameliorate (big word) this problem.  My thought is to place a section of capillary tubing between the fuel tank and the mixer.  My thought is that the capillary tubing would act as a quasi-check valve yet still allow enough fuel to go through and run the engine.  Capillary tubing ranges in I.D. from .020" to .090"which is within the orifice ranges of hit and miss mixer jets.  My thinking is that the combination of the capillary tubing diameter and the mixer needle valve would provide a fine adjustment.  Thoughts?  Why am I wrong?
Rick

Offline Jasonb

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Re: Outside the box (almost)
« Reply #1 on: December 12, 2021, 07:10:03 AM »
I saw the same thing suggested on another forum a few weeks ago as a means to stop fuel draining back. Other option is convert to propane.

Online Roger B

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Re: Outside the box (almost)
« Reply #2 on: December 12, 2021, 07:42:20 AM »
There may be a temperature/viscosity relationship that works against this. As the system warms up more fuel will flow where as you will need less, however you would only see if this is significant by experiment.
Best regards

Roger

Offline rick41

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Re: Outside the box (almost)
« Reply #3 on: December 12, 2021, 02:41:20 PM »
I saw the same thing suggested on another forum a few weeks ago as a means to stop fuel draining back. Other option is convert to propane.
Yes, I also saw that post and it is what got me thinking that an added benefit to the smaller tubing preventing back flow might be the insertion of a smaller capillary in the fuel line that would act as a flow restrictor which in conjunction with the needle valve would allow for finer adjustment of fuel flow. The capillary tube would be sized to allow a bit more fuel flow than the engine would need at maximum load with the needle valve providing the fine adjustment.  Just the musing of someone with too much time on his hands.  Rick