SS braided fuel lines

[alaric]

Hi. Some time back I bought some SS braided fuel lines for my Dellortos, and have found, on trying to fit them, that the coupling to the fuel pump is not long enough to seat on the sealing surface; the thread is correct, but the coupling screws up against the nut head before the concave sealing surface has reached the mating surface in the fuel pump. So, this won't work.

I just wondered if anyone could suggest a replacement coupling. The item I have is stamped with MS24399, has the fuel pump thread on one side and I'm not sure what thread on the other but it's very slightly larger, poss metric. The couplings on the hose are stamped with XRP, so I presume are the standard couplings and threads to use. The simplest solution would be a pipe of the same bore as the original fuel line so I could fit the original nut and olive.

I think I bought this from Matty's but it was so long ago I'm no longer sure.

All the best.

Sean.

[alexblack13]

Hi Sean,
Are you using a std fuel pump? If so they use a compression olive type fitting normally. Have you a picture of the fitting you are trying to use? can you post it?

Alex B....

[alaric]

Hi. Yes I'm using the standard fuel pump and the existing black plastic fuel lines have an olive over the pipe at the end the goes into the fuel pump. This same fitting is available on some sellers versions of the stainless braided fuel lines, but mine was supplied with an adaptor that would convert between the thread using on the fitting at the end of the fuel line, and the standard thread into the fuel pump. The adaptor has a concave sealing surface that should mate with the surface inside the fuel pump in just the same way that the olive does in the existing setup. But, the length of the adaptor means this concave sealing surface does not reach the mating surface in the pump, so, if I were to fit it and try it, fuel would come out through the threads. Since I bought this from matty's (almost sure) I can only assume one or two on the forum have the same fitting, and may or may not have noticed this problem. I'll post a pic - but dinner's about to be served and I've been playing in the garage all morning - fantastic to get out there again in the relative warmth and light.

I'll post a pic shortly.

All the best.

Sean.

[alexblack13]

Might just need some thread sealer and tightened in + left for a period of time to harden off. That would do it.

Make sure product is petrol safe..

lets see a pic' or two of the adapter and the new hose.

Alex B....

[alaric]

Hi. I'd prefer to have a sealing face doing the work rather than thread seal.

Anyay, here's a pic or two of the items that I have:

the whole assembly

Close up on the useless adaptor - pretty though

Close up of the adaptor fitted to the fuel line

Carb end close up

Centre joint

Hope that's of interest.

All the best.

Sean.

[alexblack13]

Do you have enough of a 'face' on the pump to use a sealing washer? Nice little copper washer? (soften it 1st). or a Doughty?

You should be able to make that set up work easily...

I would have no issues with the correct thread sealer. I use it all the time on WAY higher pressure that that joint would be subjected too.....

Find the correct washer, and use a thread sealer. Or how much metal would need machining off the hex to get the convex seal area to bed in the pump? 5 min job that if there is enough meat.

Great looking bit of kit though bud, and well worth fitting.

Hope this helps Sean.

Alex

[alaric]

Machining the adaptor was one of my thoughts too. I don't think a dowty seal or other form of washer to seal is appropriate as the surface on the pump is not prepared for that, nor on the connector. I'll see if the chap at work can machine it for me in the morning. I was hoping someone would be able to point me to an adaptor with a longer 3/8" thread.

All the best.

Sean.

[cliveyboy]

Sean
I enclose a picture of my hoses
They mate to the pump same as the original with 5/16" tube and an Olive.
Clive

[alaric]

Clive, that's what I'm looking for - a coupling that'll go onto the end of the pipes that I have and give me a pipe and olive to go into the fuel pump. Where did you get the coupling - I presume the braided SS pipe is a standard size, so if I trim off what's there I should be able to fit the coupling that you've used? From what I've read the couplings are fitted by pushing a metal tube into the rubber inner, then clamping the braid with a tapered nut. An alternative is if I knew what the thread was I could poss. find an adaptor that goes to a pipe instead of the one that I have at the moment.

Thanks for the photo. I like your use of plastic spiral stuff to protect the ss braid, and that yours is obviously trimmed to the lengths that you need. I bought this poss three years ago now, so as always it seems that making my own would have been a better approach. Most of it's ok though - I might decide to trim it in places.

All the best.

Sean.

[cliveyboy]

Sean
My hoses came fitted to the car but they look like they were just supplied with a plain 5/16"
tube swaged onto the fuel pump end. That way you can reuse your original fitting on the fuel pump and you just need a new olive.
My hose length looks different to yours because mine runs under the carbs then back over the top. The lengths were not ideal and needed trimming.
Your hoses look like they come up between the carbs.
Clive

[garyeanderson]

uumm, tough to recomend anything as I don't know to much about this stuff but an ms24399 is an new name for an old AN919 reducer-external thread flaired tube.
http://docs.google.com/viewer?a=v&q=cac ... JIldHcsYDw

along with this you need the appropreate tube with the correct flair. I believe that is 37 degees JIC flair at one end for the ms24399. You will need a ms20819 sleeve coupling or (AN819 old designation) and a AN 818 tube nut.
For the fuel pump, the correct olive and nut that came with the original pump. You should not need any copper to work harden or rubber seals. Like I said I don't know and you don't either, maybe get it to some one that does like where they sell these parts so you can get it right. I am making assumptions that you bought it from someone that knew about these parts and somehow you didn't get all of the parts needed to complete the system, possibly ebay or something. Guessing with fuel systems is risky and taking my advise is risky too. Google is your friend, use it. google MS24399 and it will give you a lot of info. Putting it together with other info is the trick you need to work on. These parts are U.S. mil spec and finding the right person that is conversent in mil spec stuff on this forum may be difficult, my advice is not iron clad for sure, it is a guess. Go find a racecar forum and re-ask the question and see if you can get something useful.

Gary
p.s. - the parts that "I think" you need are for the AN819-4 and AN818-4 to go to 1/4 inch tube that comes out of the fuel pump, maybe. I am not sure what the ms24399 reducer size is. No copper either steel bundy or cunifer.

[spanner]

I was hoping someone would be able to point me to an adaptor with a longer 3/8" thread.

All the best.

Sean.

Hi Sean,

You mentioned 3/8" thread. Is it actually 7/16X 20? (dash-4)

I looked at two old pumps and both have 1/2"X 20 internal threads. (dash-5)

Jim

[alaric]

Hi. I've also been hunting for an adaptor for my clutch master cylinder, which is a 3/8 unf, and in my earlier post confused that with the fuel line - that is 1/2" unf. Oops. I needed the adaptor for the clutch master cylinder because I bought a shiny braided hydraulic line, and couldn't attach it. I now have a great adaptor that's long enough to mate the hydraulic coupling on the cylinder and allows me to attach the braided line directly. Much neater than a length of copper pipe.

I'll take a look at the art of swaging and look into the parts that you've suggested Gary. Thanks for taking the time to look them out.

All the best

Sean

[spanner]

Hi Sean,

1/2 X 20 SAE thread size equals a dash -5 AN fitting with a 5/16" tube OD. http://en.wikipedia.org/wiki/AN_thread or http://www.aircraftspruce.com/catalog/hapages/an815.php

Your new, blue, hose-to-pump AN fitting is called a jump union and looks like it might be a -5 to- 6. http://www.bonaero.com/Plumbing.htm#AN919

In concept, the olive and tube are held captive by a brass tube nut.

One simple solution you can try, is to turn the pump end of the AN fitting into a tube-nut:

1) File off the 37? flare on the pump side of your new blue fitting to replicate the flat surface of the original brass tube nut.

2) Insert a short length of 5/16" tube into the fitting, add olive and install in pump.

The photo shows both 1/4" and a 5/16" tubes. The effective length on the original brass tube nut is 7/16".

What do you think? Let us know.

Jim

[alaric]

Hi. That's a neat idea. I've tried nuts on the adaptor at my local freindly eurofastener to confirm that the adaptor is 1/2" unf on the pump side, and 9/16" unf on the pipe side. I was wondering if I could mod the blue adaptor but was thinking more along the lines of using it to hold a flared 1/4" copper pipe in place. I have a decent pipe flaring tube so can put a flare on the end that goes into the convex fitting at the end of the braided pipes, put the adaptor in to press it home and the seals made by the flare and convex face. So, then I have a pipe and olive coming out the other end to feed into the pump as per original setup. I was going to hunt for a proper nut to screw in and now that I know, courtesy of your replies above, what fitting to look for, it should be an easy hunt.

As always these things seem easy in heind sight or once you have all the numbers / definitions to hand. Now if the family'd just let me get out there for an hour - it's a rainy day here in uk, so everyone's fed up stuck in the house. Luv em all to bits though of course.

All the best.

Sean.