Hot Rod Forum banner

1 - 20 of 23 Posts

·
Registered
Joined
·
13 Posts
Discussion Starter #1
Is it necessary to double flare for gas line, or, if using Russel fittings not useful or not able to accomplish with anodized type?
 

·
True Hotrodder
Joined
·
1,156 Posts
I believe you are talking about the fittings that work with steel or aluminum fuel line? Most of them are a two piece deal, you have the AN threaded nut part that fits over the fuel line and then a sleeve that fits inside the fuel line and provides the seal to a male AN fitting.

523841


523842


All you need to do to the fuel line is cut it to the length you want and as straight a cut as you can. I would recommend a tubing cutter. You will need to debur the end of the cut but that can be done with a pocket knife.
 

·
Registered
Joined
·
1,208 Posts
I believe you are talking about the fittings that work with steel or aluminum fuel line? Most of them are a two piece deal, you have the AN threaded nut part that fits over the fuel line and then a sleeve that fits inside the fuel line and provides the seal to a male AN fitting.

View attachment 523841

View attachment 523842

All you need to do to the fuel line is cut it to the length you want and as straight a cut as you can. I would recommend a tubing cutter. You will need to debur the end of the cut but that can be done with a pocket knife.
That's a compression fitting ? You don't mention flaring the tubing ??
 

·
True Hotrodder
Joined
·
1,156 Posts
That's a compression fitting ? You don't mention flaring the tubing ??
You can flare tubing of course but those two fittings make it a cut and bolt together deal. That fitting is not a compression fitting. The end of it fits inside the tube not around it and the other end of it provides the 37* flare to mate with a male AN hose fitting. It makes it very easy to get a good, tight seal.
 

·
Registered
Joined
·
13 Posts
Discussion Starter #10
I was questioning ''double flaring" which a mechanic said "always" and I am questioning his knowledge, asking here.
I have only found single here in this youtube pic. Just asking for verification.
523856
 

·
True Hotrodder
Joined
·
1,156 Posts
So what holds the tube in the fitting ?
The nut part goes on the tube first, then the fitting piece goes inside the tube and when this is connected to the male fitting end, the pressure between the male fitting and the 37* fitting locks the tube in place. The inside of the nut also has serrations to help hold the tube.
 

·
True Hotrodder
Joined
·
1,156 Posts
I was questioning ''double flaring" which a mechanic said "always" and I am questioning his knowledge, asking here.
I have only found single here in this youtube pic. Just asking for verification. View attachment 523856
Double flare is intended to keep the flare from cracking. It is always done with brake line tubing for safety. Probably not a bad idea for high pressure installations using regular brass/steel fittings. Working with AN, you are limited to single flare and that requires a special flare tool that can provide the 37* flare. Your regular flare tool for brake line will end up leaking on you.
 

·
Registered
Joined
·
1,208 Posts
The nut part goes on the tube first, then the fitting piece goes inside the tube and when this is connected to the male fitting end, the pressure between the male fitting and the 37* fitting locks the tube in place. The inside of the nut also has serrations to help hold the tube.
So its " pressure" that grips the tube , i. e. , a compression fitting as opposed to a formed flare fitting ...
 

·
True Hotrodder
Joined
·
1,156 Posts
Guess that is one way to look at it. A compression fitting to me surrounds the tube and actually gets compressed or deformed slightly. These do not, in fact they can be reused unlimited times and moved to a different piece of tubing if you wanted.
 

·
More for Less Racer
Joined
·
19,283 Posts
Brake line flaring tools are also 45°, where the AN flare is 37°...another reason your common brake and hardware flaring tools won't work.

The 37° AN flare on hard line also requires a tube sleeve, similar to what Chasracer posted but it fits outside the tube, and has a flare cut in it's face to reinforce the backside of the single flare on the hard line. Referrred to a s a "tube sleeve". It doesn't crimp on like a ferrule in a compression fitting does, and can be re-used on another line. You just have to cut the flare off the old hard line to retrieve it and the nut.

AN nut and tube sleeve on single flare line:
523866


Chasracer, can you provide a source for the fitting you described....I have never seen or heard of a AN type fitting where the sleeve just slides INTO the end of a straight cut line and the nut grips the tube. There would be nothing holding it together.
It's almost lke you are describing a hydraulic "bite"(flareless) fitting, but those are a compression style with a similar looking sleeve...and the flanged sleeve is on the OD of the tube, it gets crimped to the tube just like a ferrule when the fitting is tightened.
Anything fitting into the end of a tube is going to severely restrict flow volume.

i've searched every fitting company I can think of, Including McMaster-Carr industrial fittings, and cannot come up with anything that matches your description of a flare faced sleeve that just slides into a straight cut hard line and a nut over the OD of the tube somehow holds it all together?
 

·
True Hotrodder
Joined
·
1,156 Posts
I don't remember ever having to flare the pipe but I have some of those fittings and I will look at them tomorrow. It's been a long time since I used them as everything we do now is braided hose.
 

·
True Hotrodder
Joined
·
1,156 Posts
I guess you have to flare it - I was wrong and my apologies. I have never owned a 37* degree flare tool and still don't, so no idea of how I got that accomplished.
 

·
More for Less Racer
Joined
·
19,283 Posts
With aluminum fuel line, you can flare it single flare with a common 45° flare tool and the tube sleeve and nut will form it back to 37° when you tighten it up to the fiting nipple.

This won't work with steel line unless you've also got steel fittings, sleeves, and nuts.
Try to do it with aluminum fittings on steel line and it will just damage the aluminum fitting.
I wouldn't try this on anything high pressure either.

Most of your AN fitting companies do make a hard line adapter fitting , it is a compression fitting with a common brass ferrule in it....they are convenient to gat an AN male or female end on a hard lone so you can connect to an AN fitting hose.
 

·
Registered
Joined
·
68 Posts
I have the 37 degree add-on set for the Mastercool "universal" hydraulic flare tool. Some of the pieces are identical to the 45 degree tools--I guess they figured 45 degree and 37 degree were "close enough", at least with some tubing sizes.




Please also keep in mind that "AN" is an OBSOLETE standard, abandoned years if not decades ago. "AN" (Army-Navy) was a precision standard suitable for military and aerospace applications.

What's sold today as "AN" is generally NOT actual "AN"; it never would have met true "AN" specs, even when "AN" was a current, accepted standard.

What you're getting when you buy so-called "AN" from the usual hot-roddy sources more closely resembles the old "JIC" standards--similar to "AN", but with less-strenuous quality and construction, NOT suitable for military and aerospace, but perfectly fine on buses, semi-trucks, and hot-rods. Probably NOT suitable for Indy or Formula One, but good enough for the local dirt-track.

Calling this stuff "AN" is deceptive because it implies a level of quality that IS NOT designed or manufactured into the product, even if it does use the same thread pitches and 37 degree flare. I really wish people would stop using the term "AN" for what amounts to an industrial product.

Both the "AN" and the "JIC" standards have been replaced with new, more-modern "SAE" standards, and they're still separate--one extreme quality for military and aerospace, and the other for industrial/ground transportation.

"JIC fittings are dimensionally identical to AN (Army-Navy) fittings, but are produced to less exacting tolerances and are generally less costly. "
 
1 - 20 of 23 Posts
Top