bending new tubing

[JohnD1956]

Hi all, Looking for some words of experience on bending some new fuel lines.

I heard that you can fill a new fuel line with soft sand ( play sand) and then make your bends. This is supposed to help prevent kinking of the lines in those tight 90 degree turns.

does anyone have experience with this?

John d

[Guest imported_MrEarl]

JohnD, I've used sand in combination with the springs that you can buy at a hardware for bending copper tubing and that works pretty well on long sweeps. a tube bender works better on short tight bends I think.

[Guest Andynator]

The sand trick is correct, but not play sand - it's too coarse and compacts when you bend the line. There is a sand especially for this that is very fine - almost like the very fine sand that hotels (used) to put in their ashtrays. How's that for a comparison? I don't know what it's called, you may have to ask around.

Goes without saying that you have to be extra dilligent to get it completely cleaned out. Strong blast of air works. You need to pre-clean the inside of the line to remove any oil residue from the manufacturing. Making sure the sand is completely dry helps too. Spread it out on a cookie sheet and dry it out in the oven first, but don't let your wife catch you doing it.

This sounds like a lot of work, but it's really not, and the bends are VERY nice. Mandrel is still a must.

[NTX5467]

If you have a "pattern" in an old line, this can be good. If you will be fabricating "from scratch", be sure to plan out just how you want the line to run before you start bending anything. Some people use some defluxed welding rod to make a general pattern for the finished line configuration.

Measuring the total length of the finished tubing is very important. In doing fuel lines, you can buy the pre-flared tubing at the auto supply in particular lengths (sticks)--why the length you need is important.

In what the factory did, they can and have done some compound bends that are tighter (smaller radius) and closer together than what you might be able to do in the field. Sometimes, they can be simplified somewhat and still get from point A to point B. With the correct finesse and planning, things will look like they came that way.

I have a simple tubing bender with 4 slots in it, plus the "holder" on one side of it. I have had good luck using it, but the key thing is to NOT get in a hurry as you can still kink the line if you aren't careful. THEN you have to start over with a new stick of tubing.

In an engine situation, all of the bends will not be in the same "plane". That means that you make one bend and then rotate the tubing a little bit and make another bend, repeating as necessary until you're done. Like I said, if you plan things out and take your time, rechecking the fit as you go, you can end up with a highly OEM-looking item. It might take two or more tries to get what you want, so if the first one isn't "right", don't feel discouraged (been there, done that).

If you want to spiff up the look, you can take some 600 grit (red Scotchbrite) and polish the exterior of the line after you get it all bent and ready for final installation. Then you might follow it with some 1000 grit Scotchbrite for a nicer finish. Just depends on the "look" you are after. Some clear coat (spray clear "ignition system protector" enamel) can keep it looking nicer.

In the general configuration of the line, remember to keep things generally "sloped" upward from the fuel pump to the carb(s). Even just a slight slope is better than "flat" (with respect to the other engine components). Keeping the line away or out from behind other engine components is a plus too. Having a picture as a pattern of what you hope to end up with can be a plus too.

Happy bending!

NTX5467

[Guest imported_widomski]

All I read is extremely good information but it has been my experience that tubing benders seem to always work the best especially on the small tubing of gas and brake lines. I have at least 4 different ones because each one bends the tubing in a slightly different radius. I know this could be expensive especially if it is a one time shot but the benders are great for brake lines, vacuum and transmission lines. You might want to check with others at car shows, cruises, etc to see if they can be borrowed. my cars

[carbking]

Bluepoint makes a good bender for the hobbyist if bends with a radii of less than 1 1/2 inches are not necessary. These are available at better automotive parts houses. If smaller bends are desired, check with the local machine shop to see if they have a bending machine. These machines are fairly pricey for the hobbyist. Ours, with minimal tooling, was around $5K.

We tried the sand, and didn't care for the results. We found to get the best results with a hand bender, to oil both the bender and the tubing; and go slow.

Jon.

[Pete O]

Hi John- I see you're located in New York. Anywhere near Long Island? I had a set of gas and vacuum lines bent by Centereach Auto Parts on Long Island. I made a pattern using copper tubing. The copper was easy to bend by hand and to make those tight turns. I gave the copper patterns to Centereach Auto, and they made steel lines. They fit almost perfectly with only little adjustments needed.

[JohnD1956]

Thanks for the replies everyone. I am not from Long Island, I'm in Schenectady County outside the city of Schenectady. I have two different tube benders and have done some bending before. It is definitely easier as you develop experience. But that 3/8ths line is a challenge.

For this particular car, an 89 Lesabre t type, the bends need to be near perfect. The original lines are laid side by side and there are five lines all within 1/4 inch of each other running through multiple brackets. The car has a 3/8th fuel supply and a 5/16th fuel return for the fuel injection. The local Buick dealer has these and they have that GM end on them. We got the 5/16 near perfect but kinked the middle of the 3/8th line. The nice thing though is the lines came with the gravel guards.

Anyway we have to re-do the 3/8th line and then tackle the 1/4 vent line and we are probably going to put in the new brake lines while we are there. Sure wish I had a lift for this.

Thanks again for the comments. I found the one about oiling the line interesting. I never did that before. Does this really help?

[carbking]

The lines kink because something is unable to slip. Oiling the lines and the tool allows free movement, and minimizes kinks.

Jon.