mark79,80

In order to seal the carburetor fuel line I have to wrap teflon tape
around the fitting. I had a new fitting that screws into the
carburetor in which the fuel line is connected, and installed it to
see if I could seal the fuel line without the teflon tape.
Fuel line still leaked with the new fitting.

On a 1979 I have the fuel line seals to the carburetor without
teflon tape.

Do I need to replace the fuel line from the fuel pump or is
using some teflon tape acceptable?

rcread

You definitely shouldn't have to use teflon tape to seal your fuel line. If you must, leave the first few threads uncovered so that a piece won't come loose and enter your engine.

MotorHead

Fuel lines shouldn't need teflon tape. That being said I have used it in the past on fuel line gauges that leaked on me. The white tape will disintegrate you have to use the yellow tape

63mako

Don't use teflon tape. Use teflon paste for natural gas pipe fittings. Works just as good and won't clog your carb if some does break loose.

MotorHead

Not an argument just a discussion. As pointed out by another poster above, you don't put the tape on the first couple of threads, no where for anything to go in that case.

Second, are you certain any paste that "breaks loose" is not going to cause any harm to any pin hole passage in the carb ?

63mako

TFE paste is what I always use. As you said apply carefully, don't put it on the first couple threads.

MotorHead

It is kinda funny because I have switched to the paste now for last couple of years

71406

Is it possible that you have a stainless fuel line going to the carb? Stainless is harder than the original material and can be harder to seal.

mark79,80

I have never replaced the line and is probably oeriginal, so
not stainless.

For those recommending paste: what type is it? For
natural gas?

...Roger...

So whats the teflon doing,actually sealing or lubricating the threads so the fit is tighter?

63mako

TFE paste. Available at all hardware stores.

ripforrey

The theory, in the water industry, is the teflon is a lube that allows for a tighter fit of the threads.

...Roger...

Thats what I thought also but thats on tapered pipe.In the case of the pipe thread the threads are doing the sealing.In this case are the threads taking over doing the sealing or is the added pressure from the lube forcing the tapered seat tighter? Hmmm

68 NJConv 454

I think I agree with DWncchs.
As far as I know all fuel line is sealed with a tapered seat, the threads don't do the sealing. You don't want teflon tape or anything else to prevent the tapered seats from reaching eachother. They need to reach eachother to seal correctly, the threads are just there to force the tapered seat surfaces together.
However, I can visualize an old or poorly constructed fitting with worn threads having issues forcing the taper seat surfaces to eachother. In this case I would replace the fittings. The teflon tape could be used to fill in the worn threads to force the tapered seats together...but like mentioned above you don't want the tape or paste getting near the tapered surfaces to obstruct a good seal.
Personally I would replace the fitting or section of tubing. I wouldn't take a chance with fuel in the engine compartment.:smash:

noonie

I think he is referring to the 1" fine threads that seal the inlet/filter housing to the body casting. A common problem with both the older and later qjets. The older had 7/8" threads and the later 1".

They can be helicoiled, the kit is very expensive but you can have it done for aaround 50 bucks.

Here's 1 guy
http://sparkyscarbs.com/

Not condining him, just a lead.

MotorHead

The tape or paste ( for fuel lines ) is a bubba fix at best but if it works then you saved yourself allot of time and aggravation

BigBlockTank

If you read OP's post, I think he's talking about the fuel line to the carb, from the pump. He's changed the carb fitting, and it's still leaking, from the fuel line. He stated that it was probably original.

Buy a new fuel line, fitting, carb, hose clamps, anything to make that thing stop leaking. Fiberglass burns very quickly.

vetteguy75

You can get a small tube at any auto parts store.

7T1vette

Either live with a "Bubba" fix or buy a new fuel line. I'd buy the new line...

billla

'nuff said about paste vs. tape

Sometimes the problem is simple - the flare is not all the way down into the fitting. Inspect the flare and the fitting and make sure there's not an issue with the fit. Then seat the flare and tighten the fitting.

Seems simple...but it's bit me a couple of times with factory-style fittings. I had a buddy bring me an LT-1 with the factory split block and it was leaking everywhere with tape everywhere....30 minutes later everything was tight with no sealant in sight.