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  #1  
Old 02-18-2009, 07:44 AM
Mich48041 Mich48041 is offline
 
Join Date: Apr 2008
Location: Riley TWP MI
Posts: 3,094
Default Page 28-03 Tube bending

For the 3/8 tube between the fuel tank and the fuel pump, I cut a piece 24" long and flared one end. I think that grease does a better job then oil on the point of the flaring tool. Just use your thumb and forefinger right next to the flaring tool shaft. This is one case where more is NOT better. As soon as you feel resistance, stop turning. A sleeve will not slide past a bend so make sure it is in position and orientated correctly before bending. A nut WILL go around a bend. I have bender similar to this one: http://www.aircraftspruce.com/catalo...ehdrbender.php
It will not bend as close to the end as Van's bender. I did manage to get it a little bit closer by placing the stepped-down portion of the sleeve under the bender hook and with the shoulder of the sleeve against the left side of the hook. Keep the nut back out of the way. After making the first bend, I laid the long part of the tube on the bench with the short end pointing straight up and measured from the table up to the shoulder of the sleeve and found it to be 2 7/16". This distance is called the stub-up. Knowing this distance helps with subsequent bends. If anyone wants to read more about stub-ups, here is a link: http://www.porcupinepress.com/_bending/StubUps.htm The rule of thumb for bending stub-ups is that the end that you measured from goes on the left side of the bender. Since the 3/8" tube takes a shortcut around corners, it gains about 3/4" in length going around a 90 degree bend compared to the square-corner distance.
For the second bend, I measured the drawing of the tube from top of the page to bottom at 6 9/16". Subtracting the stub-up distance of 2 7/16" equals 4 1/8". I set the pump end of the tube on the table with the long tube pointing straight up and measured from the table up and put a mark at 4 1/8". Put the tube in the bender with the pump end on the LEFT and the tank end on the RIGHT and put the mark on the left side of the hook. After making the bend, do not forget to put both nuts and the remaining sleeve onto the tube before making the flare on the tank end.
The vertical part of the tube that connects to the tank needs to be 3 7/16" long. Subtracting 2 7/16" for the stub-up gives 1". Make a mark 1" from the tank end of the tube. Put the tube in the bender with the tank-end to the LEFT and the pump-end to the RIGHT and with the mark on the left edge of the hook.
I made the 15 degree bend last. I marked the tube 6" as shown for dimension A-A and lined the mark up with the 15 degree line on the bender. I was hoping that 24" was going to be long enough and it turned out to be exactly right. The tube lined up perfectly with the drawing. How lucky could I be?
My luck did not hold though. I made a perfect length of tube to connect the valve with the flow meter. It was the right length. The angles were bent correctly. I remembered to put the nuts and sleeves on. It was beautiful. Then I realized that it would not fit through the bushing in the bulkhead with the nut and sleeve and flare already on both ends. LOL
Here is what I learned installing the fuel system: Buy an extra 12 feet ($16) of tube from Van's well in advance of working on the fuel system. It will be needed.
Joe Gores
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  #2  
Old 02-18-2009, 08:13 AM
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Geico266 Geico266 is offline
 
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Location: Huskerland, USA
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Quote:
Originally Posted by Mich48041 View Post
Here is what I learned installing the fuel system: Buy an extra 12 feet ($16) of tube from Van's well in advance of working on the fuel system. It will be needed.
Joe Gores
Good advice.
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  #3  
Old 03-01-2009, 08:16 PM
Slane Slane is offline
 
Join Date: May 2008
Location: Hillsboro, OR
Posts: 159
Default Fuel Line Bending, flaring and torquing...

Thanks Joe,

I followed your methods and the end product was very good, IMHO. Question though, how do you judge the appropriate amount of flare on the tube endings? Also, when you install the line to the pump on p. 28-03, how do you gauge the amount of torque in such a tight space? The builder's manual (5P) indicates I should go for between 75-125 inch pounds.

How are others judging the flare and the torque?

Scott
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  #4  
Old 03-01-2009, 09:17 PM
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Geico266 Geico266 is offline
 
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Location: Huskerland, USA
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My tube bender has a stop on it that stops the tube at about the right spot. The flare is too big if the nut won't go over it.

Torquing the nuts can be done with a torque wrench or the 1/4 turn method. Tighten the nut finger tight and then wrench it 1/4 turn more. I found a spec sheet on this and it seems to works well.
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Last edited by Geico266 : 03-01-2009 at 09:20 PM.
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  #5  
Old 03-01-2009, 10:41 PM
Mich48041 Mich48041 is offline
 
Join Date: Apr 2008
Location: Riley TWP MI
Posts: 3,094
Default Section 28 Fuel system

More fuel system tips:
Add step #0 to the plans as follows:
STEP 0. Order extra tube from Van's a week before working on the fuel system!
If desired for appearance, the tube can be rolled between the workbench top and a short piece of 1x6 to make it straighter.
Make sure that all 3 of F-1276C plastic blocks lay flat against the bottom skin before installing the fuel lines. The under side of the blocks should be counter sunk to fit over the nuts that are on the studs. And those nuts should be tighter than the ones that go on top to hold the two halves together. The drill bit will grab plastic and pull itself all of the way through faster than you can blink. Put the plastic blocks in a drill press vise and clamp the vise down. It is not heavy enough to resist lifting by the drill bit.
When the directions specify a certain length of tube to be cut, add a half inch or so. The roll of tube that Van's supplies is long enough. Your bender might be different than Van's bender, or your bends might not be at the exact same angle. You can always cut the excess off later.
Do as told when instructed to put the nut and sleeve on. Do not think that you can slide the sleeve on from the other end. If the tube is not perfectly round for the whole distance, the sleeve will not slide from end to end.
Page 28-04 Figure 3: Unless you have Van's bender, you will not be able to make the S-shaped bends close together as pictured. Make them further apart and less than 90 degrees. Do not make a bend too close to the bulkhead.
Page 28-04 Step 3: The 3/8 tube will not go through the plastic bushings. You will have to file the little tabs inside of the bushing, either in place, or remove the bushings and put them into a vise so that the tabs are pushed inward while you file.
A very small amount of grease on threads and on the sleeve collar where the nut rubs will prevent galling.
To clean filings out of the tube before final assembly, feed a nylon fish line through the tube. Use the fish line to pull twine through the tube, followed by a blast of air. Air alone might not remove all particles, especially if there is any oil inside of the tube.
Page 28-04 Step 5: The fuel pump mounting bolts can be loosened to facilitate connecting the pump to valve fuel line.
Page 28-05 Step 2: Safety wire the 4 screws before mounting the gascolator to the firewall. I left the bottom drain off for now so that I do not break it off accidentally.
Page 28-05 Step 4: Fit in place before making final cut and flare. Template is not actual length.
Page 28-05 Step 5: Cut the tube a 1/2 inch longer. It is not going to be the exact length anyway. Leave some room for your tube cutter to work. Not only do you have to remember to put the nut and sleeve on the tube before making the final flare, but also remember to put the tube through the bushing in the bulkhead first. You can get a better angle to work by pulling the bend into the bushing.
Page 28-06 Step 3: It is easier to bend the return line upward towards the tank if it is sitting on top of the 3/8 tube instead of beside it.
Page 28-06 Step 6: Make the bends first before cutting the length and making the flare.
Page 28-06 Step 7: At the firewall, the bottom bend is 90 degrees. The bend next to it is about 45 degrees or whatever is required to kick the tube 1.75" to the port side and into alignment with the bulkhead bushing. The bends in the vertical part near the engine mount bracket offset the tube 7/8 inch away from the firewall. Note that the clamp holds the tube an 1/8" away from the firewall and also holds it up 1/4" from the bottom skin. After making the bends, the cut the forward end and flare it.
Page 28-06 Step 8: Wrap the flap mixer to prevent it from scraping the fuel line. Or get a helper to hold the fuel line down.
Page 28-06 Step 10: Due to the proximity of the bulkhead fitting to the bulkhead flange, the bulkhead fitting might not be horizontal. The tube must be bent to mate straight-on with the fitting. The plastic bushing will hold the tube while you push the end up about a half inch. Then push the tube forward so there is only 2" protruding through the bushing. Then pull the tube down. Repeat until the tube lines up with the bulkhead fitting. Once the return line is installed, press down on it where it passes underneath the flap mixer. Put the top halves of the F-1276C nylon spacer blocks on to hold all of the plumbing in place.
Do not ask me how I learned these tips. LOL By the way, did I mention that you should order extra tube before starting?
Joe Gores
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  #6  
Old 03-02-2009, 11:30 AM
Mich48041 Mich48041 is offline
 
Join Date: Apr 2008
Location: Riley TWP MI
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Default flares and torque

Quote:
Originally Posted by Slane View Post
Thanks Joe,

I followed your methods and the end product was very good, IMHO. Question though, how do you judge the appropriate amount of flare on the tube endings? Also, when you install the line to the pump on p. 28-03, how do you gauge the amount of torque in such a tight space? The builder's manual (5P) indicates I should go for between 75-125 inch pounds.

How are others judging the flare and the torque?

Scott
Scott,
I am happy to hear that my posting helped you bend the fuel line. As for flaring the ends, I measured the outside diameter of a couple of my flares on 3/8 tube and found them to be 0.49" to 0.50". The 1/4" tube flares measured 0.325. I am not saying this is correct, only that is how mine are. Have you watched the EAA Hints for Homebuilders flaring tips?
http://www.eaa.org/video/homebuilder...Id=11670888001
I think it is better to make a flare slightly under size rather than oversize. You can pressure test your system to check for leaks. If the flare is too big, it might not leak initially, but could eventually if the flare is too big and cracks.
I did not measure the torque of the nuts because my torque wrench only uses sockets that will not fit onto tube nuts. It needs to be tight enough not to leak but not so tight as to damage the parts. If you really want to measure the torque, you can use an open end wrench along with the fish scale that Van's recommends in the tool list. Suppose that you want 100 inch-pounds of torque. You attach the fish scale to the wrench at say 8 inches. Divide 100 inch-pounds by 8 inches and you get 12.5 pounds. Pull on the fish scale until it reads 12.5 pounds. Once you get the feel for it, you can judge how hard to tighten the nuts without measuring the torque.
Joe
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  #7  
Old 05-27-2011, 08:00 PM
Mich48041 Mich48041 is offline
 
Join Date: Apr 2008
Location: Riley TWP MI
Posts: 3,094
Default Fuel line hint

To prevent the fuel fitting nut from sliding down the tube where it is difficult to reach, I slid an "O" ring onto the tube. Some of you might be thinking that it is hard enough to remember to put the sleeve and nut on before flaring. How am I going to remember an "O" ring?
Joe Gores
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  #8  
Old 05-29-2011, 10:42 AM
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MacPara MacPara is offline
 
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Good idea! I think to avoid this now, after flaring the tubes, I will just wrap a cable tie around the tubes.
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