56 fuel tank connection

[txturbo]

I have a 56 that the fuel line was rusted in two in a couple places when I got it about 6 years ago. To get it running I just added a barbed fitting screwed into the tank and ran a rubber fuel line to the engine compartment as a temporary fix. After a long hiatus, I’m getting back to work on it repairing a transmission problem. So while I’m waiting on parts, I tackled fabrication of a whole new steel fuel line. At the tank, I’ve run into a problem. This also applies to the tank from my parts car. The original steel line was just screwed into the fitting on the tank. The threads in that fitting go in at least 3/4” and there doesn’t appear to be an inverted flare bevel at the bottom. The steel line is the standard inverted flare type. The inverted flare nut will screw into the fitting but there is no way that is going to seal. Is there another fitting that screws into the tank to match up to the inverted flare tubing?

[J. Gomez]

I have a 56 that the fuel line was rusted in two in a couple places when I got it about 6 years ago. To get it running I just added a barbed fitting screwed into the tank and ran a rubber fuel line to the engine compartment as a temporary fix. After a long hiatus, I’m getting back to work on it repairing a transmission problem. So while I’m waiting on parts, I tackled fabrication of a whole new steel fuel line. At the tank, I’ve run into a problem. This also applies to the tank from my parts car. The original steel line was just screwed into the fitting on the tank. The threads in that fitting go in at least 3/4” and there doesn’t appear to be an inverted flare bevel at the bottom. The steel line is the standard inverted flare type. The inverted flare nut will screw into the fitting but there is no way that is going to seal. Is there another fitting that screws into the tank to match up to the inverted flare tubing?

Dan,

Check this thread - > http://forums.cadillaclasalleclub.org/index.php?topic=158035.msg448280#msg448280

There is a brass double flare aka ferrule that goes in between the tube and tank. You can probably make one or just buy it, there could be other supplier out there not sure.

Good luck..!

[fishnjim]

You're kinda lucky you never had a serious fire in 6 years.   Static, leaks, impacts, pinches, etc. 
"Caution" for others with same "temporary" fuel line conditions.   Follow OEM or current fuel/DOT safety stds.   Just because it hasn't, doesn't mean it can't.   Serious accidents happen when a string of low probability events occur.   Have to lower the risk up front and decouple the chance for stringing.
Looks like that tank needs some attention as well.    Carbs don't like rusty gas. 
common issue;
I found same "fix" plus a crude electric assist pump when I got my '58 and immediately removed and replaced the line, etc. with new.  It had a new SS tank, but PO's not diligent with the delivery system. 
The new replacement lines aren't made to the factory specs*, and I had to change out the shorter supplied end fitting for the longer original, and still use gender adapter.  Surprisingly the tank was correct just different metallurgy.    I'm not sure what end fitting was correct for '56, but mention if it doesn't tighten/seal.  Flare fittings are flat threads so need a certain degree of engagement.   
I guess it's just one of those eng'g. design "oops" they had back in the day.   The person designing/spec-ing the line didn't talk to the tank supplier.   It took a few years to get out of the system.   Those were paper system days, when a lot harder than CAD to spot/correct errors...   and after they make a few hundred thousand for stock and copies of the drawings, they're hard to purge.  Adding a small revision in the legend doesn't alwayw get picked up.   Workers will hoard old info.   Used to drive me...
* - which you can not obtain new.   Would have to be made in machine shop.

[Daryl Chesterman]

As others have said, there is a serious rust problem that you will be constantly fightingâ€"even with a fuel filter!  As for fittingâ€"if the threads in the tank are national pipe thread , then this fitting, with the appropriate sized ends will do the job, and is available at many automotive jobbers.

https://www.amazon.com/Hillman-Group-58342-Inverted-Fitting/dp/B00NUFNFXG/ref=asc_df_B00NUFNFXG/?tag=hyprod-20&linkCode=df0&hvadid=194861420852&hvpos=&hvnetw=g&hvrand=10028642244303237395&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9033826&hvtargid=pla-315303005751&psc=1

If the fuel line is 5/16" and the female bung in the tank is 1/8" pipe thread, the Eaton part number is 402 x 5, which you can get at a NAPA store.  If the fuel line is 5/16" and the female bung in the tank is 1/4" pipe thread, the part number is 402 x 5 x 4.

Daryl Chesterman

[txturbo]

Thanks but that is a picture of the rusty tank from my parts car, not the one I’m using. I just took the picture of that one instead of trying to crawl under the other one.

[Daryl Chesterman]

It is good to hear the pictured tank is not the one you are using!!!  The fitting I linked to on Amazon is still the one you need, depending on the tank threads.

Daryl Chesterman

[J. Gomez]

I would not recommend adding an extension at the tank inlet fitting which is shorter than the total inlet length as it will not seal against the inside flare end.

The ferrule is about 0.4” and the tube thread fitting is also around 0.4”, so you would need at least 1” to properly seat the extension and the end of the extension would require to be flare as well.

[txturbo]

Guess I’ll just make something on the lathe or get a longer tubing nut.

[J. Gomez]

Guess I’ll just make something on the lathe or get a longer tubing nut.

Dan,

The same tube thread fitting length from your picture above and the ferrule inside would suffice in connecting the fuel line.

If you have a lathe or the use of one the job of making the ferrule would be much easier and simpler. In my case I had to use the basic tools file, dremel tool to grind the angle on one side as I used a brass fitting with the flare end cut it to length and grind/file the other end and the OD to fit inside.

Good luck..!

[txturbo]

In case anyone was curious what the fuel pickup looked like inside the tank...

[txturbo]

I’ll probably just turn down one of these couplers. Easier than making one from scratch.

[txturbo]

Got one roughed out. Still need to turn it down to a smaller diameter to fit inside the tank bung. If anyone else needs one, let me know.

[J. Gomez]

In case anyone was curious what the fuel pickup looked like inside the tank...

  that does not look like the '56 fuel tank pick up line  the one for the '56 is not flat at the end and is a bit shorter from what I recall and the end is just open

[J. Gomez]

Got one roughed out. Still need to turn it down to a smaller diameter to fit inside the tank bung. If anyone else needs one, let me know.

I've used one like this one which I had handy and cut the end grind and file the end to the same angle and file the thread still in the line with no issues. 

[txturbo]

Don’t know. It came out of a 56 tank.

[Daryl Chesterman]

There was this same problem posted in 2009, and if you scroll down about 3/4 of the way through the replies, there is a picture of the brass insert fitting that is what is being discussed.

    http://forums.cadillaclasalleclub.org/index.php?topic=106620.0

Daryl Chesterman

edit to add that reproductions are available on Ebay: 

https://www.ebay.com/itm/174101023570?chn=ps&norover=1&mkevt=1&mkrid=711-117182-37290-0&mkcid=2&itemid=174101023570&targetid=1068323855670&device=c&mktype=pla&googleloc=9033826&poi=&campaignid=11612432550&mkgroupid=112073031326&rlsatarget=pla-1068323855670&abcId=9300456&merchantid=101491398&gclid=Cj0KCQiAvP6ABhCjARIsAH37rbQZUVzmS79PZZfFEnascABIlcngxIJvDjtpC0Jbi46H9nEL64rUFjsaAm2bEALw_wcB

[txturbo]

The brass one came up a little short so I made a new one with some steel. I think I have the length right now.

[The Tassie Devil(le)]

I would be persevering with a brass one as a steel one in this task will run the risk of deforming the seat on either side, and thereby possibly making the use of a brass one in the future, being prone to leaking.

If I can recall the necessity for a collapsible material, as in brass, or even copper, the task is not to seal each end, but to collapse around the tube, thereby creating a perfect seal so the petrol cannot squeeze past the inner diameter.

These fittings work by compression, and a steel one won't collapse, and create the required seal.   Even when tight, it might be possible to move the tube back and forth.

Bruce.

[txturbo]

Look at the pictures I posted. It’s not a compression fitting. It’s a 45 degree inverted flare tubing on both sides. There is no collapsing taking place.

[The Tassie Devil(le)]

I agree that the picture you posted of the steel fitting is not collapsible, but the correct fitting should be collapsible, so it does two things.   Seals the fitting at the 45 degree seat, and the inner diameter collapses around the tube to fully seal the tube so the fuel cannot simply escape up the sides.

Bruce.