-AN6 Fuel line leaks - How to seal ?

[mcwho]

New QFT Carb - Out with the Edelbrock - Fuel Leaks
OK, I bit the bullet and got a Quickfuel ss-650-an from Wayne. Also got the SUmmit 4150 Dual fuel line. I did the settings on the T-SLots as recommended. The old carb is a Edelbrock 1806. Never could get it right, its a single inlet and the New carb is a dual inlet, that why I had to get a new fuel Feed Line.

I did al lthe settings for the QFT and the engine started right up, no stumbles etc. The first leak was where there is a plug for a Fuel Pressure Guage. That's fixed, snug.

I was always under the inmpression that you should NOT use any kind of Teflon tape, sealer etc. with AN fittings, they are -AN 6

All of the other fittings are snug as well, I see a leak in the rear, looks like its leaking onto the fuel bowl then down to the intake manifold. Never had any issues like this with the old carb/fuel.

It maybe possible that the gaskets that are right next to the carb are bad, its kinda hard to see back there. I am using the gaskets that came with the Summit Fuel line kit 220-0106. There were also white gaskets that came with the carb, maybe I should have used them instead.

Regarding the Dual fuel line kit I have leaks in several places, what should I seal the fittings with?

[NAZ]

Don't use Teflon tape on any fuel or oil lines and fittings. In fact, I submit that there is nothing on an automobile that Teflon tape should be used on period! If it's a tapered thread pipe fitting use Loctite PST -- leave the Teflon tape to the plumber that works on your home water lines. BTW, Teflon tape will do nothing for leaks in straight threads as they don't seal in the thread like pipe fittings do. All your carb fittings should be straight threads. I suspect you'll find your leak is a gasket or seal problem. If you purchased a used carb you may have other issues causing a leak such as warped sealing surfaces or deep scratches.

[mcwho]

The point of my POst is that I have read to NOT use Teflon tape on fuel line fittings.

I did some research and one article said that -AN fittings use O rings, I don't know, I can find 20 answere to each question on here. I also have a white liquid, but don't want to use that If I am going to possably return the Summit part.

The other stuff I have have is called Permatex Thread seat with PTFE
I would think the standard would dictate if the thread is straight or tapered.

The Fittings in question are this link!
https://www.summitracing.com/parts/sum-220106

I read the reviews and saw that about 35% OF THEM HAD LEKAGE ISSUeS !

[NAZ]

It appears that the fuel feed assembly you have uses aluminum washers (seals) where the inlet adapters mate to the carb. Is this the part that is leaking? Make sure you have the correct fuel bowl inlet fittings that match your carb. If the carb uses the O-ring style the flat washers (seals) won't seal. Ports that are designed for O-rings use either a register or counter sink so that the O-ring is not crushed when tightening the fitting. Ports designed for seals will have a machined flat boss around the female threaded port. QuickFuel uses both types but I don't know which they use on your model.

[mcwho]

It appears that the fuel feed assembly you have uses aluminum washers (seals) where the inlet adapters mate to the carb. Is this the part that is leaking? Make sure you have the correct fuel bowl inlet fittings that match your carb. If the carb uses the O-ring style the flat washers (seals) won't seal. Ports that are designed for O-rings use either a register or counter sink so that the O-ring is not crushed when tightening the fitting. Ports designed for seals will have a machined flat boss around the female threaded port. QuickFuel uses both types but I don't know which they use on your model.

Yes, the washers that came withy the fuel line kit are Aluminum, actually I think all the parts other than the washers are probably aluminum.with something black on them. The washers that were in the carb, behind the adaptors as supplied are the white plactic or nylon?

The adaptor to the top right is what was on the carb, The adaptor in the left have the same formt mating surfaces as the ones removed. Tomorrow I am gonna try again using the white washers, that area was where most of the leaking was.

thanks for your help

see picture

[edwardb]

The -6AN fittings in those connections don't have any O-rings. The seal is 100% metal-to-metal on the taper and seat. The threads are not part of the sealing function. So no thread sealant. I used the Quick Fuel inlet kit with my Quick Fuel carbs. This one: https://www.summitracing.com/parts/q...0-ss/overview/. Didn't have any leak issues. I used the gaskets that came with the kit for the carb connection, which were some type of white plastic. Also no thread sealant. Only place I used any sealant was the gauge port as directed in the instructions. It's an NPT fitting and sealed via the tapered threads. I have bought my share of stuff from Summit (today's understatement...) but generally stick with name brand stuff vs. their in-house brand. Even though I suspect it's all supplied by recognized mfg's.

[NAZ]

The photos show clearly that you have the correct fuel log for your application. I suspect you'll find that the leak is due to the seal (the flat washer looking part) and trying the plastic seal vs the aluminum is a good choice. edwardb used the plastic seals with success so chances are good that they will work for you. Any scratches or damage to the seals or sealing surfaces can cause a leak. Also, over tightening the fittings into the bowls can damage the seal and or the bowls causing a leak. Good luck, I'm sure you will get your leak fixed. And I'm sure that carb will work well in your application.

[mcwho]

You Guys are both correct, I will be surprised if using the other (white) washers don't fix it.

I did notice a difference between the two regarding the the seating area next to the threads.

On the shorter adaptor, the one that came with the carb, the seat inner surface has a beveled section, like at a 45 degree angle
wheras the seat on the fuel line kit adaptor (the longer one) had a raised boss in that area. They are definitely different though.

It looks like the white washer inner surface does NOT touch either of these areas though.

see attached.

[NAZ]

That bevel you see on the OEM part is simply a very robust way to reduce stress risers on a 90-degree machined angle. A sharp edge on an inside corner is an invitation for the part to fissure in that area when stressed such as when tightening. Let us know how the plastic seals work out for you. Others reading this will be interested too as 4150 style carbs are very popular.

[mcwho]

Just finished reinstalling plastic/nylon and fuel lines.

Hooray....NO LEAKS !

Took it out for a test drive, Hooooahhhh ! Lots more low end torque, mid range is awesome. !

[edwardb]

Just finished reinstalling plastic/nylon and fuel lines.

Hooray....NO LEAKS !

Took it out for a test drive, Hooooahhhh ! Lots more low end torque, mid range is awesome. !

Good news! Welcome to Quick Fuel carbs. Felt exactly the same when I went from a Holley vacuum secondary to the Quick Fuel double pumper.

[NAZ]

Good job! Got interrupted before and had to leave but I was also going to say that that register you see on the new part may be why the aluminum seals leaked. If the register bottoms out before the thin seal does it will leak. The register is there to center the seal so it is concentric with the boss the seal mates with. Anyway, you have the problem solved -- now on to tuning that carb so it runs perfect on your engine and altitude.

[mikeinatlanta]

Glad to see you have it fixed. To clarify, the fitting connections at the carb in your pic are not AN. The tapered connections elsewhere on your dual feed line are. If you get a leak at an AN, first check for damage on the tapered area, then you can get a thin tapered sealing washer to go inside, called a AN repair washer. As others have said, never ever use any type of sealant on an AN fitting.