Leaking Fuel Line Inlets on a 1967 L71

[Rob A.]

I searched the forum and the predominate solution has beento use Loctite 545 thread sealer. Is this still the best product out there? And is it the right solution for my situation given the leak location?

[Joe L.]

Re: Leaking Fuel Line Inlets on a 1967 L71

After changing the oil and converting my oil filter back tothe original canister on my survivor ’67 L71 I ran the car only to find thatthe lines entering the Holley carburetors are now leaking. They have neverleaked before so this is a new issue.
I searched the forum and the predominate solution has beento use Loctite 545 thread sealer. Is this still the best product out there? And is it the right solution for my situation given the leak location?
What is perplexing is that they have never leaked before. Idrive that car monthly but it does sit the majority of the time. I run VP fuelin it and never pump gas to avoid ethanol issues and increase the fuel life. I’veattached a picture, it is leaking just above the large nut where there appears to be a round bushing or gasket. If you enlarge the picture you can see fuel spraying out.

Thanks for your input and help.

Rob------


If the leak is emanating from the tubing nut, Locktite or any other sealer will do no good, at all. The tubing nut serves only to hold the tubing flare against the seat in the carb fitting. No sealing is accomplished at the threads.

If the leak is emanating from the fitting on the carburetor, that's a different story. A new gasket or sealer might help here.

[Hector G.]

Re: Leaking Fuel Line Inlets on a 1967 L71

I would agree with Joe. I too have had this issue but thankfully it has been resolved. I would only add that if you plan on tightening the tubing nut or for that matter, the fitting, make sure to use the correct tools. Unless you've have vast experience working with tubing nuts and are careful, make sure to use a flare nut wrench. You could ruin the flare and only increase the leak. There is also a technique used when tightening flare nuts. Good luck.

[Rob A.]

Re: Leaking Fuel Line Inlets on a 1967 L71

Rob------


If the leak is emanating from the tubing nut, Locktite or any other sealer will do no good, at all. The tubing nut serves only to hold the tubing flare against the seat in the carb fitting. No sealing is accomplished at the threads.



If the leak is emanating from the fitting on the carburetor, that's a different story. A new gasket or sealer might help here.

To make sure we are talking the same fittings, I've added an arrow to the picture showing where the fuel is leaking. The leak is coming from where the larger fitting goes into the carburetor float bowl. There appears to be a washer and small metal gasket that seals the larger fitting into the carb bowl. The flare nut on the fuel line that fits into this larger fitting appears to be fine.

This leak is occurring on the front and center carbs. Who makes the best replacement parts? I assume that I will need to remove the fuel line fittings first to remove the carb fitting then replace the gasket/seal.

[Joe L.]

Re: Leaking Fuel Line Inlets on a 1967 L71

To make sure we are talking the same fittings, I've added an arrow to the picture showing where the fuel is leaking. The leak is coming from where the larger fitting goes into the carburetor float bowl. There appears to be a washer and small metal gasket that seals the larger fitting into the carb bowl. The flare nut on the fuel line that fits into this larger fitting appears to be fine.

This leak is occurring on the front and center carbs. Who makes the best replacement parts? I assume that I will need to remove the fuel line fittings first to remove the carb fitting then replace the gasket/seal.

Rob------


Yes, if that's where the leak is emanating from, you will first need to remove the tubing nut. Then, you remove the fitting. The gasket is a metal gasket which seals by compression. In my opinion, these gaskets should not be re-used. In other words, once the fitting is loosened and removed, the gasket should be replaced on re-installation. These gaskets can be obtained from Holley or from other carburetor parts suppliers. You can use a sealer on the threads as long as you know it's a sealer impervious to gasoline. Many common sealers are not.

When you install the tubing nut and tighten it after installation and tightening of the fitting, you must hold the fitting with with a wrench while tightening the tubing nut.

[Mark M.]

Re: Leaking Fuel Line Inlets on a 1967 L71

Rob I have seen these 3x2 holleys leak in many areas and it is very common. There are many fittings, 3 bowl inlets and a squirt pump (on center) carb. Not sure but the problem appears to be the 1 inch bowl inlet fitting on that carb. I custom made an open end 1 inch wrench by cutting down both sides very slender to fit optimally in the tight space given on the float bowl. A number of tries until it fit well enough to not pinch into bowl but get in to hold and turn the fitting at the different positions possible in this tight space. This tool and a 5/8 flare nut wrench are a piece of mind with a tri carb vette. A 67 we brought to the nations this year leaked at the same spot just as we where to pull up at ops parking. It was an easy fix . The 1 inch bowl nut must be held while the flare nut is loosened first. Than tighten bowl nut than flare nut, this is assuming its just loose. I've retightened accel pump screws , float bowl screws and the bowl inlets nuts as mentioned. With the heat and vibration of these engines, the original style gaskets, these cars leak now and then. Good luck

[Rob A.]

Re: Leaking Fuel Line Inlets on a 1967 L71

Rob I have seen these 3x2 holleys leak in many areas and it is very common. There are many fittings, 3 bowl inlets and a squirt pump (on center) carb. Not sure but the problem appears to be the 1 inch bowl inlet fitting on that carb. I custom made an open end 1 inch wrench by cutting down both sides very slender to fit optimally in the tight space given on the float bowl. A number of tries until it fit well enough to not pinch into bowl but get in to hold and turn the fitting at the different positions possible in this tight space. This tool and a 5/8 flare nut wrench are a piece of mind with a tri carb vette. A 67 we brought to the nations this year leaked at the same spot just as we where to pull up at ops parking. It was an easy fix . The 1 inch bowl nut must be held while the flare nut is loosened first. Than tighten bowl nut than flare nut, this is assuming its just loose. I've retightened accel pump screws , float bowl screws and the bowl inlets nuts as mentioned. With the heat and vibration of these engines, the original style gaskets, these cars leak now and then. Good luck

Mark, Thanks for the input. I will give your suggestion a try this weekend. Like I mentioned in my original post it is perplexing that this started occurring and on two of the three carbs at the same time (or at least that's when I noticed it....)

[Michael H.]

Re: Leaking Fuel Line Inlets on a 1967 L71

Rob,

I used a copper flare seal ( flare savers ) that you can use which helped me seal my fuel lines if it's leaking at the line going into the big nut. The flare savers are made for the aviation industry.

Mike

[Steve G.]

Re: Leaking Fuel Line Inlets on a 1967 L71

The most common cause of leakage at the large nut with the gasket is the failure to loosen the flare nut fitting when tightening the fitting with the gasket. Highly unlikely you need to replace the gasket, they get used a dozen times over without leaking. But if the large fitting was retightened at some time without loosening the flare nut the line is twisting as the big nut tightens. Eventually the twist in the lines loosens the the large nut.

[Rob A.]

Re: Leaking Fuel Line Inlets on a 1967 L71

The most common cause of leakage at the large nut with the gasket is the failure to loosen the flare nut fitting when tightening the fitting with the gasket. Highly unlikely you need to replace the gasket, they get used a dozen times over without leaking. But if the large fitting was retightened at some time without loosening the flare nut the line is twisting as the big nut tightens. Eventually the twist in the lines loosens the the large nut.

I finally had time this afternoon to work on my '67. As suggested, I loosened the flare fitting and the tightened the large nut then tightened the flare nut. This sealed everything up nicely. Thanks for all the suggestions and help.

[Steve G.]

Re: Leaking Fuel Line Inlets on a 1967 L71

I should also have mentioned that when you tighten the flare nut you need to hold the large nut from turning any further. Even once the large nut has been tightened, if you don't hold it while you tighten the flare nut it can turn slightly with the flare nut resulting in that twist of the line that wants to spring back and loosen the large nut.