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Glow engine fuel tank plumbing question

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Old 10-11-2017, 10:38 AM
  #1
douglas racer
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Default Glow engine fuel tank plumbing question

I'm rebuilding an old Sig Kougar and using the fuel tank out of another old plane. This fuel tank has a straight vent line going into it. IE. it doesn't curve upwards into the air space at the top. 50% of the time it's submerged. Other than fuel coming out of the vent line if its removed from the muffler and lowered below the vent line in the tank is there a performance problem with this? The previous airplane seemed to run flawlessly with this set up. I don't own a tube bender to change it. Any input would be appreciated. Thanks for looking.
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Old 10-11-2017, 11:02 AM
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You will never be able to fill the tank completely without the vent at the top of the tank. Otherwise, the engine does not care if the vent is submerged. No different from flying inverted.
I have bent vent line tube in small sections. As long as you can still blow through it freely, it will be fine.
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Old 10-11-2017, 01:10 PM
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douglas racer
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Ahhhhhhhhh the light bulb just went on. That's why I was doing 5 minute flights instead of my usual 8 to avoid dead sticks. Doh. Thanks a lot, that makes perfect sense now I think about it.

Last edited by douglas racer; 10-11-2017 at 01:14 PM.
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Old 10-11-2017, 01:16 PM
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Old 10-12-2017, 03:19 PM
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Just a slight bend toward the top of the tank should help . I have some springs that I slide over my fuel tube and then I can put a pretty good bend in if I need to . Sometimes just getting a longer tube and slanting it to the top is enough. ENJOY !!! RED
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Old 10-12-2017, 04:14 PM
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Something that no one has mentioned yet is the bubble on one side of the tank. That is there for the vent tube to go into so you can completely fill the tank IF the tank is installed upright. Just for sake of argument, when I install a fuel tank in a boat, I put the vent in the top right corner and the fuel pick up in the bottom left so I can totally empty the tank. This only works since the tank is installed on a sloped surface so the top is at the front of the boat and the bottom is at the rear. Since I don't have to worry about banking or inverted flight, I actually get to use hard pick up lines inside the tank where, in an aircraft, the clunk type pick up is almost mandatory
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Old 10-12-2017, 05:07 PM
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When I have a short tubing end to bend I put the end of a drill bit in the tubing. Bend it a little pull it out some . Repeat this until I get the bend I want.

You could make one bend to the top then cut an angle on the end of the tube.
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Old 10-12-2017, 07:16 PM
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I found a bent tube in another tank that fits perfectly into the bubble in this tank. That combined with a 2 ounce bigger tank should allow me to wring it out for 10 minutes. Thanks for the replies.
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Old 10-13-2017, 11:28 AM
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Hi!
The brass tubing does not have to go entirely up into the bubble...just bend the brass tubing slightly and put a piece of silicon tubing on it and it will go into the bubble.
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Old 10-13-2017, 08:22 PM
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No tubing bender? No problem! Take a short piece of scrap house wiring and remove a 5"-6" long piece of one of the wires (red black or white it doesn't matter) and strip off the insulation so you have only the copper wire. Insert the copper wire all the way thru the brass or aluminum fuel tank tubing and proceed to bend the fuel tubing over a strong curved metal surface such as large socket. The copper wire inside the fuel tubing will prevent the tubing from kinking. Bend it a little at a time and you end up with a nice smooth bend. When you have the tubing bent to the curve and size you want pull the copper wire out of the bent tubing with your pliers and install the tubing into the fuel tank. Save the copper wire for reuse on your next fuel tank assembly.
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Old 10-16-2017, 02:41 PM
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I have nothing new or original to add to this, but Red head mentioned the springs that go over the tubing. I got some of that at Harbor Freight, but have not used it yet. I have also heard of guys using weed wacker line to put inside. That is similar to the copper wire idea which seems good too. Maybe the trimmer line might pull out easier.
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Old 10-16-2017, 03:26 PM
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Quote:
Originally Posted by 52larry52 View Post
No tubing bender? No problem! Take a short piece of scrap house wiring and remove a 5"-6" long piece of one of the wires (red black or white it doesn't matter) and strip off the insulation so you have only the copper wire. Insert the copper wire all the way thru the brass or aluminum fuel tank tubing and proceed to bend the fuel tubing over a strong curved metal surface such as large socket. The copper wire inside the fuel tubing will prevent the tubing from kinking. Bend it a little at a time and you end up with a nice smooth bend. When you have the tubing bent to the curve and size you want pull the copper wire out of the bent tubing with your pliers and install the tubing into the fuel tank. Save the copper wire for reuse on your next fuel tank assembly.
That's a creative idea for bending tube. I'll try that some time. Thanks everyone. Thumb up. :-)
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Old 10-17-2017, 07:46 AM
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Copper tube work hardens so it is worth while annealing it before trying to bend it. Heat it till it is red hot and quench in cold water.
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