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Old 04-19-2018, 10:41 PM   #1
dmjlambert
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concerns about flare fitting on fuel pump and carburetor

I have a 1969 CST/10 with a 350 engine, mostly stock except a GM HEI and a 1986 Quadrajet.

I am replacing the hard fuel line between the fuel pump and carburetor because it was not shaped well, not routed a way that makes it easy to disconnect in order to replace fuel filters, and I think it may have had a problem that requires it to be tightened too much.

The line is a green painted steel line commonly available at auto parts stores. They come long and straight and with double flare and fitting on each end. A couple years ago is when I installed this, I cut it to length and bent it with a tubing bender, and put the fitting on and flared the end. The flare tool and the bending tool were loaners from the auto parts store, in new condition, and worked well. At the time I installed this I had a different carburetor with the inlet at a slightly different position compared to my current carburetor. So the fit is not ideal. Plus, I did a regular flare and not a double flare. The double flare factory fitting was on the fuel pump. I tightened it with the minimum torque required to get it to stop leaking. I had to tighten it very much.

Now fast forward to today. I destroyed the fuel pump in the process of trying to loosen the fitting, it was overtightened a Ridiculous amount. This was the double flared side. I had to use less force to remove the single flared side from the carburetor, but I still think it was too tight. I've been putting off doing this work because I knew I would have a bad time with it. The worst is over, I have disconnected the damned thing. I have some experience replacing fuel pumps so I'm not worried about doing that. And I think bending the new fuel line to shape will also be fine.

My question for you guys is: are there any tips to put the flare fittings on or treat them in advance so I don't have to over tighten them to prevent fuel leaks?

Last edited by dmjlambert; 07-29-2018 at 08:43 PM. Reason: punctuation
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Old 04-19-2018, 11:43 PM   #2
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Re: concerns about flare fitting on fuel pump and carburetor

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I don't know if you have the line already or not but I have started using a product called NICOPP. It is a nickel/copper line that is much softer than steel and it bends and flares much easier. It won't rust and you can get coated fittings for it too. I have had good luck getting it to seal with a minimum of torque on the fittings. If you type "NICOPP fuel line" into Google Search you will see who handles it in your area. It is a little more expensive but worth it as far as I'm concerned......

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Old 04-19-2018, 11:57 PM   #3
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Re: concerns about flare fitting on fuel pump and carburetor

there are company's that make fuel lines for your application's.Now GM from what i've been told by a lot people you need a runner line some where in between the Fuel pump and the carb or the line with crack and spray gass all over your engine and we all know what happens when that happens But lon your computer browser type in Fuel line to Rochester carb
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Old 04-20-2018, 12:00 AM   #4
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Re: concerns about flare fitting on fuel pump and carburetor

What Leon said. The nickel / copper stuff flares like butter. It also seals well because it is softer. I use a hydraulic flaring tool & have to go easy on the nicopp stuff. If there is a downside it's that it bends too easy, I have a hard time making "crisp" looking lines.
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Old 04-20-2018, 10:23 AM   #5
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Re: concerns about flare fitting on fuel pump and carburetor

If you’re not good at flaring (like most of us) then just buy the already flared lines available at most parts places. They come in different lengths with different ends.
When you install any flared fitting, just snug it up then loosen it, snug up harder, loosen again and repeat going a little tighter each time. This process heats the metal slightly and the two surfaces mate. Smooths them togethor. Once they’re mated and leak free you can remove them and install them again without going thru the first time process again.

And don’t use any sealer on the flare threads.
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Old 04-20-2018, 11:10 AM   #6
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Re: concerns about flare fitting on fuel pump and carburetor

Quote:
Originally Posted by LockDoc View Post
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I don't know if you have the line already or not but I have started using a product called NICOPP. It is a nickel/copper line that is much softer than steel and it bends and flares much easier. It won't rust and you can get coated fittings for it too. I have had good luck getting it to seal with a minimum of torque on the fittings. If you type "NICOPP fuel line" into Google Search you will see who handles it in your area. It is a little more expensive but worth it as far as I'm concerned......

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yep. thats the stuff you want to use (nicopp) unless you go with a flex braided hose with AN fittings.
the nicopp bends easy.. simple bubble flare where rubber if any attaches.
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Old 04-20-2018, 12:25 PM   #7
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Re: concerns about flare fitting on fuel pump and carburetor

I've come to appreciate the copper-nickel line. Some people have used plumbing copper tubing for brakes and fuel, which is a big mistake. It will work-harden from vibration and eventually crack. The high nickel content in the NiCopp tubing eliminates that. I personally do not like having any neoprene in line from the pump to the carburetor, since it can get brittle and leak. I do have this on my truck, because my FiL put an inline filter between the pump and carb. I'll address that eventually, but those pieces of hose are checked often.
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Old 04-23-2018, 08:42 PM   #8
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Re: concerns about flare fitting on fuel pump and carburetor

I would like to thank everybody for your input. You guys made me think when talking about the copper and softer metals. geezer#99 your advice about snugging, loosening, and repeating, is excellent; I did it. I decided to stay with steel line and bend a fresh one after reading some more about all the options on the web, pros and cons of each metal. You guys talking about the softer metals sealing with minimal torque helped lead me to my ultimate solution. Copper flare gaskets from Grainger. No leaks.
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Old 04-23-2018, 10:09 PM   #9
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Re: concerns about flare fitting on fuel pump and carburetor

Those are meant for single flare lines, just so you know. But they will conform to the double flare fitting, so it's all good. We used those to seal up single flare fittings on spacecraft fuel systems, which have to not leak for the lifetime of the thing, which might be 30 years or so, like the Hubble (which I did not work on); just pointing out an old system that is still working. If you break the fuel lines open, you should either use new conical washers or anneal the ones you removed in the oven, provided they are not dented. If dented, just toss them. Do know, however, that many millions of vehicles rolled off the assembly without washers in the fittings.
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Old 07-29-2018, 08:05 PM   #10
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Re: concerns about flare fitting on fuel pump and carburetor

Here is another related parts find. The car parts stores in my area don't carry the Quadrajet inlet gaskets for the 1" inlet fittings. They have the fuel filters, but have discontinued the inlet gasket and can't order them either.
https://www.ebay.com/itm/253758885907
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Old 07-29-2018, 08:40 PM   #11
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Re: concerns about flare fitting on fuel pump and carburetor

Just a quick reminder re fuel filter between pump and carb...

Please make sure its a metal clad fuel filter, not one of those plastic cased ones...

Have had too many people bring me vehicles with fire damaged engine bays caused by these plastic filters...

NiCopp lines are excellent...and those copper seals are a good second alternative.

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Old 07-29-2018, 10:12 PM   #12
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Re: concerns about flare fitting on fuel pump and carburetor

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As long as the fuel filters were brought up, if you run a Q-jet don't forget to change the small filter in the fuel inlet on the carb. They catch the finer stuff that most of the plastic or metal inline filters don't and will make you wonder why your truck just quit running like it is out of gas....

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Old 07-29-2018, 10:18 PM   #13
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Re: concerns about flare fitting on fuel pump and carburetor

Yup. Those sintered bronze fuel filters even stop water!
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Old 07-30-2018, 08:23 AM   #14
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Re: concerns about flare fitting on fuel pump and carburetor

I'm pretty much the ultimate DIY'er, but with fuel lines, for what little they charge for all new parts, I'd just order a new one unless you have some weird carb/manifold/pump setup.
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Old 07-30-2018, 06:33 PM   #15
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Re: concerns about flare fitting on fuel pump and carburetor

repro fuel lines. use a factory bronze or paper in line filter in the carb but also an after market in line clear plastic one somewhere in the line between the tank and the pump.

That way you can see the garbage that would have ruined your pump and caused you no end of frustration down the road.

garbage is garbage and if there alot in your tank plan on a new tank eventually, dont wait too long either because new pumps, rebuild kits, and under hood fires along lonely dark roads late at night soon will cost more than a new tank
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