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  1. #1
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    What should i use

    One of the connections on my recently fitted metal fuel lines using “Atec” fittings, running to the Holley carb on my SBC has started to weep petrol where the connector screws into the secondary fuel bowl( see attached image) . The connector is as tight as I dare get it, and the connectors in both the primary and secondary fuel bowls are fitted without any thread sealant and the connector in the primary fuel bowl is dry.

    Should I remove the connector and wrap some PTFE tape around the thread ,as I believe PTFE tape is petrol resistant, if not what should I use ?

    Or should i remove the metal washer in between the fuel bowl and connector and replace it with a fibre washer ?

    Paul.

    AK Huddart Chevy 383 Stroker, BMW Royal Grey Metal Metallic , 5 speed Jaguar Getrag , Holley 670cfm 4 barrel street Avenger Carb, 450 BHP at flywheel , 460 Ibs/ft torque, and luvin it !

    " We dont stop playing because we grow old, we grow old because we stop playing" - George Bernard Shaw.

  2. #2
    I would suspect ptfe tape is best bet IF fuel resistant, or Blue Hylomar IS a fuel resistant sealant, but not sure how a sealant would perform under pressure.
    Hopefully someone more knowledgeable along soon...

  3. #3
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    I'm not sure PTFE will help as I think the mating faces do the sealing and not the threads. Although I could be wrong.
    Have you got the correct type crush washer in there?

  4. #4
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    I did a bunch of reading recently and I believe you're right, Incey - standard Holley et al is 7/8-20 parallel threads, face sealing with supplied plastic or fibre washers.. IIRC my QuickFuel has plastic sealing washers (I say plastic but they'll be something fuel safe, obviously).

    I think, but this could be entirely wrong, that the sealing washer should be softer than the metal either side of it - so aluminium/copper on a steel sump, plastic/fibre/O-ring on aluminium carb? I do see 'china made' kits with steel washers but it looks more like the US-made stuff has fibre/plastic or O-rings..

    Also.. what's the shite shmoo coming out of the ATEC fitting? Looking up that part number it's a female JIC fitting which seals on the conical inner face and needs no sealant, so I hope that isn't liquid PTFE

    You could replace the fuel bowl fitting with one of these, which has the O-ring included and your female JIC (ATEC fitting) will screw on to: https://www.ebay.co.uk/itm/382268966...0AAMXQCndRh4ul
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  5. #5
    Join Date
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    Seems that the washer is intended to be the sealing mechanism (or why would it be there) so my instinct would be to fix that rather than the thread.
    Looks metallic, hopefully Aluminium rather than Steel, this should be OK as long as it’s soft (annealed) but if used multiple times will work harden and not seal as it should.
    Petrol proof plastic or fibre will (probably) be softer and better able to conform to the mating faces hence seal easier but may not be as robust as metalic.
    What about the mating faces (on carb' and fitting)? Do they have any damage which would prevent the washer from sealing?

    Agree with Aaron, the tapered seat/JIC fitting should not need or have PTFE on thread, if it needs that then it’s defective.

  6. #6
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    I think the pukka holley ones are rubber coated nickel.

  7. #7
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    Quote Originally Posted by incey1966 View Post
    I'm not sure PTFE will help as I think the mating faces do the sealing and not the threads. Although I could be wrong.
    Have you got the correct type crush washer in there?
    There is no crush washer fitted, just the shiny aluminium washers which came supplied with the Atec fittings.
    Paul.

    AK Huddart Chevy 383 Stroker, BMW Royal Grey Metal Metallic , 5 speed Jaguar Getrag , Holley 670cfm 4 barrel street Avenger Carb, 450 BHP at flywheel , 460 Ibs/ft torque, and luvin it !

    " We dont stop playing because we grow old, we grow old because we stop playing" - George Bernard Shaw.

  8. #8
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    Quote Originally Posted by aaronjb View Post
    I did a bunch of reading recently and I believe you're right, Incey - standard Holley et al is 7/8-20 parallel threads, face sealing with supplied plastic or fibre washers.. IIRC my QuickFuel has plastic sealing washers (I say plastic but they'll be something fuel safe, obviously).

    I think, but this could be entirely wrong, that the sealing washer should be softer than the metal either side of it - so aluminium/copper on a steel sump, plastic/fibre/O-ring on aluminium carb? I do see 'china made' kits with steel washers but it looks more like the US-made stuff has fibre/plastic or O-rings..

    Also.. what's the shite shmoo coming out of the ATEC fitting? Looking up that part number it's a female JIC fitting which seals on the conical inner face and needs no sealant, so I hope that isn't liquid PTFE

    You could replace the fuel bowl fitting with one of these, which has the O-ring included and your female JIC (ATEC fitting) will screw on to: https://www.ebay.co.uk/itm/382268966...0AAMXQCndRh4ul
    Thanks for the link Aaron, it looks like the built in "O" ring mates inside a recess and not on the same mating surface that the existing aluminium washer is currently sat on , or have i got that wrong. Would this "all in one" fitting have any advantages over just fitting a softer washer ?

    Taking on board what Aaron and others have said, i now suspect that the mating surface on the secondary fuel bowl must have slight imperfections, which is allowing fuel to sneak past the washer, so i reckon you are right , i do need to fit a softer washer, and while i have it apart, I will see if i can see any imperfections on the mating surfaces.

    The white shmoo that Aaron spotted is PTFE tape and is belts and braces and was only put on the treads to make doubly sure it didn't leak on those joints.

    I am currently looking after our recue dog which had 3 nasty operations this week and is very poorly, and i was supposed to be taking the cobra to the Jag E-type 60th show this saturday, so for the time being, i will just pinch up the fitting a bit more and see if it stops the leak to let me take the cobra, if not i will go in my tin top and hopefully have more time to do this job properly .

    Thanks for the input guys, sounds like you have hit the nail on the head .

    Paul
    Paul.

    AK Huddart Chevy 383 Stroker, BMW Royal Grey Metal Metallic , 5 speed Jaguar Getrag , Holley 670cfm 4 barrel street Avenger Carb, 450 BHP at flywheel , 460 Ibs/ft torque, and luvin it !

    " We dont stop playing because we grow old, we grow old because we stop playing" - George Bernard Shaw.

  9. #9
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    Quote Originally Posted by psh View Post
    Thanks for the link Aaron, it looks like the built in "O" ring mates inside a recess and not on the same mating surface that the existing aluminium washer is currently sat on , or have i got that wrong. Would this "all in one" fitting have any advantages over just fitting a softer washer ?
    I think you're right - it probably squishes into the 'inner corner' of the joint; I still need to figure out how I'm attaching the carb to the fuel regulator/filter on mine so if I end up buying those I'll let you know!

    The white shmoo that Aaron spotted is PTFE tape and is belts and braces and was only put on the treads to make doubly sure it didn't leak on those joints.
    Aha - the joint there (as long as I'm looking at the right fittings in their catalogue) seals on the conical face like a brake flare, no PTFE needed as the threads aren't involved in the seal at all (my clutch lines use the same style fittings).

    I am currently looking after our recue dog which had 3 nasty operations this week and is very poorly,
    Never mind the rest, this is the important bit! I hope the pup recovers quickly
    My DeDion build diary..
    Hon Sec of the Digidash branch of the Unpopular Kit Car Design club

  10. #10
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    Never use PTFE tape as pieces can break off inside the thread and clog the carb. You can however use the PTFE paste if required.

    I would use a fibre washer either side of the adapter and you should have no need for any PTFE.

    I have banjo connections fitted HOLLEY 26-25 5/16in. SWIVEL FITTING (2625). You should be o.k. with just fitting the fibre washers on your set up.
    Last edited by jon1d; 10-06-21 at 12:44 PM.
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