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Old 01-11-2022, 02:09 PM
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Originally Posted by LoneWolfSS454 View Post
H-Bill, Thank you for test fitting the larger Proflex hose on the barbs you had on hand. Things went about as I had expected.
These are the clamps I was looking at getting (link below) but do you guys know of any better ones (clamps that might have greater clamping force), not that these won't do the job?

https://www.valleyviewrc.com/du-bro-...r-18-fuel-line
I've used those type before without issue. I've also slipped a second piece of tubing (a ring if you will) over the main line and never had an issue.
I'll let others chime in on what they use and experiences.
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Old 01-11-2022, 02:15 PM
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With regard to how well Proflex holds up to the cold.
I had a piece of large Proflex tubing, small Proflex tubing and finally a 1/4" OD x 1/8" ID piece of Viton outside in the shade for the last four and a half hours. Temperature to start was a brisk 4 deg F and has now warmed up to a balmy 24 deg F, but wind chills are around 12 deg F.
Analysis...
Both the large and small Proflex tubing pieces were stiffer then the piece of Viton tubing.....not a lot, but definitely notable when I went to flex them.
If they are the same basic material why might that be.....I believe the thinner tubing wall of the Proflex material is impacted by the cold temperatures quicker then the thick wall of the Viton material.
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Old 01-11-2022, 03:18 PM
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That analysis sounds very reasonable. I interpret the "end result" to mean; Don't fly in the cold, unless the plane has been kept inside a heated room/area! Even then, when out flying when it's really cold will likely cause fuel starvation at some point (when the tubing cools down enough).


In somewhat related news, I built a large scale (1/5th?) Hpi Baja 5B-SS dune buggy back in mid-2012, powered by a gas/oil, ESP race-ported Zenoah G290RC engine. I just checked the (still original) external fuel line, a transparent yellow line (with an equally small black line going into the fuel tank), and eyeballing a metal 12" ruler it looks to be 3/16's OD. It's also as hard as a rock, showing very little flex to speak of. Trying to squeeze it "flat" produced no noticeable movement. Whatever the black line is, it was only a fraction softer, but still very hard, yet it showed no (external) signs of dry rot/cracking. I couldn't see the black line inside the (empty) tank, which could be a bad sign as the screw-on filler cap is near the rear?

Given how this engine was a very powerful "Screamer" (besides the porting it has a wicked looking "tuned pipe", a very noisy pipe that'll hurt your ears even at 30+ feet away) and ran like a "scalded ape" (before a large cloud of talcum-powder like fine dust, of my own making, got sucked through the multi-layer oiled foam air filter), I can hardly believe it ran as good as it did with such a small fuel line! I looked at the source (Dave's Discount Motors - DDM) where I got the buggy, engine, and other parts, and they now offer a Tygon fuel line "conversion kit" which includes a larger ID fuel line which claims to increase power! No measurements were given, on any of the various fuel lines I saw for sale.
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Old 01-11-2022, 05:56 PM
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After thinking (more) about how well the skinny 3/16's OD fuel lines kept the high revving modified Zenoah G290 fed on my heavy (21.2 lb) buggy, I can't help but wonder if the standard Proflex line would adequately feed a typical 40cc boxer-twin plane engine? The situation I'm thinking about would only have a short piece of the standard Proflex line inside the fuel tank (clunk to internal tank fittings) with 1/8" ID Tygon line the rest of the way to the engine.
With that "out loud wondering" done, I think I'll still buy the larger Proflex line, just to be on the "safe side of good fuel delivery". If need be, I can always use "safety-wire fuel line clamps" (or another improvised clamping method) to make sure the larger line stays secure any place it may not fit tight enough.


Has anyone tested plastic soda straws submerged in gas and oil for any length of time? DDM has some "interesting" braided material that might be useful in place of a straw, but I have no idea if this is a true statement?
https://www.davesmotors.com/braided-...el-line-sleeve
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Old 01-11-2022, 06:42 PM
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1/8 ID works well on DA-170's.
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Old 01-11-2022, 07:35 PM
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Is that like comparing the 3/16" OD (likely 3/32" ID) fuel line on my buggy, to using the same 3/32 ID line on a 40cc twin engine (where as most would use 1/8" ID line - which "on the surface" seems like it might be a touch on the small side for a 170cc engine)?
I suppose without knowing the exact fuel flow requirements for the various engines, and maximum fuel line flow rates (for their size), it's hard to say what (alternative) sized lines can feed what engines safely and adequately? The engines are too expensive (imho) to risk with inadequate flowing line to perform extensive testing (for most of us anyway). This leaves most of us to play it safe, right? If the 1/8" ID line does safely feed the 170cc engines, while most 40cc owners also use the same 1/8" ID line, I'd think the fuel flow requirements (overall) might be much lower than many of us think, especially with the smaller displacement gas engines?
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Old 01-12-2022, 12:38 PM
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There is no reason to go smaller than 1/8 inch on smaller engines. The carb inlet nipple is pretty much standard on 1/8 on all R/C carbs (glow as well).
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Old 01-18-2022, 03:47 PM
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I tried a plastic straw inside the tank to keep the proflex from folding. Test was a failure. The plastic softened and started to come apart. Dont do it. Went back to brass.
Edwin
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Old 01-18-2022, 06:06 PM
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Ouch!
Thanks for answering that sir. I'd planned on using a brass tube with a piece Proflex hose to the clunk regardless, but others can learn from your experience.
To have "options" I ordered both sizes of the Proflex hose (in 2' lengths). The larger size will be going into the (external - fueling) gas can for certain.
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Old 01-19-2022, 11:14 PM
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Quote:
Originally Posted by Edwin View Post
I tried a plastic straw inside the tank to keep the proflex from folding. Test was a failure. The plastic softened and started to come apart. Dont do it. Went back to brass.
Edwin



That's odd, I've used plastic straws for years with no problem.
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Old 01-19-2022, 11:30 PM
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How does viton hold up as smoke tubing and connecting to the muffler? Hold up to heat well?
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Old 01-20-2022, 06:11 AM
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Originally Posted by flatspinjim View Post
That's odd, I've used plastic straws for years with no problem.

Not all plastic straws are made of the same plastic. And some plastic straws are now being made of sustainable and/or biodegradable materials.
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Old 01-20-2022, 09:03 AM
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How does viton hold up as smoke tubing and connecting to the muffler? Hold up to heat well?
Viton is rated to 400 deg F.....I've used it with no issues in the past
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