HELP! (Stupid question)

[bdmcgee]

I'm ordering new braided fuel hose line to run from my mechical fuel pump to the carb. . . and. . . I don't know what the "AN" stands for? I'm new to wrenching and I'm learning as I go. The JEGS catalog has hose listed -4AN all the way to -16 AN. What's stock on a 1969 GMC? Thanks for any help. . . .

FYI - My "old" line runs back from the pump to the firewall, then up. The previsou owner had a pressure regualtor mounted on the firewall that I'm removing, then returning the feul line back to where it was 'new'. . . .

[El Jay]

AN thread
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-6 AN fitting
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The AN thread is a particular type of fitting used to connect flexible hoses and rigid metal tubing that carry fluid. It is a US military-derived specification stemming from a joint standard agreed upon by the Army and Navy, hence AN. The standard is sometimes mistakenly referred to as "Air Force-Navy", but it dates back to World War Two, before there was a separate US Air Force.

AN sizes range from -2 (dash two) to -32 in irregular steps, with each step equating to the OD (outside diameter) of the tubing in 1/16" increments. Therefore, a -8 AN size would be equal to 1/2" OD tube (8 x 1/16 = 1/2). However, this system does not specify the ID (inside diameter) of the tubing because the tube wall can vary in thickness. Each AN size also uses its own standard thread size.

AN fittings are a flare fitting, using 37° flared tubing to form a metal-metal seal. They are similar to other 37° flared fittings, such as JIC fittings, which is their industrial variant. The two are interchangeable in theory, though this is typically not recommended due to the exacting specifications and demands of the aerospace industry. The differences between them relate to thread class (how tight a fit the threads are) and the metals used.

Note that 37° AN and 45° SAE fittings and tooling are not interchangeable due to the different flaring angles. Mixing them can cause leakage at the flare.
Size comparison AN size -2 -3 -4 -5 -6 -8 -10 -12 -16 -20 -24 -28 -32
Tube OD (Hose ID) 1/8" 3/16" 1/4" 5/16" 3/8" 1/2" 5/8" 3/4" 1" 1-1/4" 1-1/2" 1-3/4" 2"
SAE thread size 5/16-24 3/8-24 7/16-20 1/2-20 9/16-18 3/4-16 7/8-14 1-1/16-12 1-5/16-12 1-5/8-12 1-7/8-12 2-1/4-12 2-1/2-12
Pipe thread size (NPT) 1/8-27 1/4-18 3/8-18 1/2-14 3/4-14

[edit] See also

[my67chevytruck]

AN 6 = 3/8, and is what most ppl run for fuel line, but below is a description for you.


AN ("A" for Army,"N" for Navy)
This standard was originally designed for the U.S. Military. AN fittings are measured on the outside diameter of the fittings, in 1/16 inch increments. Thus, an AN 4 fitting would have an external diameter of approximately 4/16", or 1/4", and an AN 6 fitting would have an external diameter of approximately 6/16" or 3/8". In this case, approximation is important as AN external diameter is not a direct fit with an equivalent NPT thread.

[71 super]

As stated above you will need to get a -6 (dash six) line approx. 3 feet in length, some black electrical tape to tape hose before you cut- will make it easier when you install fittings, a 3/8 to -6 nipple, a 90* -6 fitting and a fitting to go into whatever type of carb you are running. When you cut the hose you should have a cut off wheel or at least a sharp hacksaw to cut the shealth. Lube the fittings well and be sure they install securely. Also unless you are very careful regular wrenches will scar your new fittings pretty bad as they are anodized aluminum and are soft.

[bdmcgee]

THANK YOU!

[Longhorn Man]

why not go with 3/8 steel brake line? There is no real advantage on the steel braided stuff other than being "pretty"... and it will be very abraisive... don't let any rubber or plug wires lay on it, the braided line will eat right through it.
you can get a line and the tools to bend it for less than 25 bucks.
just seems pointless to me.

[ll____b0t____ll]

Originally Posted by Longhorn Man

why not go with 3/8 steel brake line? There is no real advantage on the steep braided stuff other than being "pretty"... and it will be very abraisive... don't let any rubber or plug wires lay on it, the braided line will eat right through it.
you can get a line and the tools to bend it for less than 25 bucks.
just seems pointless to me.

So is that why N.A.S.A uses it on its spacecraft cuz its pretty?

[Longhorn Man]

if the conditions under your hood are anything close to what nasa deals with.... or nascar for that matter, then you have some bigger issues to deal with.
it's overkill.
i figured i'd get flamed... but expected better arguments than nasa.
that's not even apples to oranges.

[steves1967]

Steel brake line is thin and, over time, can work harden and crack- spraying fuel all over the engine. SS braided hose can leak, but rarely does, however the benefit to SS braided hose is flexibility, durability, and ease of installation- plus, as was stated, it looks "pretty".

Also the NHRA doesn't allow for more than 12" of exposed rubber hose in a fuel system..

[ll____b0t____ll]

Originally Posted by Longhorn Man

if the conditions under your hood are anything close to what nasa deals with.... or nascar for that matter, then you have some bigger issues to deal with.
it's overkill.
i figured i'd get flamed... but expected better arguments than nasa.
that's not even apples to oranges.

First off as a forum staff person shouldnt you be following the rules of this site?
It is clear the OP has decided to use the braided hose and was seeking help with size NOT weather or not you think the product is worthwhile.
So by you posting to say what he wants to do with his truck is a waist of money with no facts to back up those claims as they are only "your" opinions and further by saying you expected to be flamed and expected arguments , doesnt that seem like maybe you just shouldnt have posted to begin with?
Sounds like baiting to me.
Just becouse you dont see the benifit in using a quality part as apposed to rubber hose and hose clamps doesnt mean others cant.

Everyone has a right to their own opinion but why discourage others from using a part that even though is more money holds more benifits?

And as far as the conditions under my hood , I replace whatever i can with billit alluminium and hoses with braided cuz i like to fix a thing just once.
And I didnt have to work for N.A.S.A or be a rocket scientist to figure that out.

[El Jay]

Originally Posted by ll____b0t____ll

First off as a forum staff person shouldnt you be following the rules of this site?
It is clear the OP has decided to use the braided hose and was seeking help with size NOT weather or not you think the product is worthwhile.
So by you posting to say what he wants to do with his truck is a waist of money with no facts to back up those claims as they are only "your" opinions and further by saying you expected to be flamed and expected arguments , doesnt that seem like maybe you just shouldnt have posted to begin with?
Sounds like baiting to me.
Just becouse you dont see the benifit in using a quality part as apposed to rubber hose and hose clamps doesnt mean others cant.

Everyone has a right to their own opinion but why discourage others from using a part that even though is more money holds more benifits?

And as far as the conditions under my hood , I replace whatever i can with billit alluminium and hoses with braided cuz i like to fix a thing just once.
And I didnt have to work for N.A.S.A or be a rocket scientist to figure that out.

Not my area, but we don't really need a pissing match by anybody.

Howsabout we all back up a few steps, take a couple of deep breaths...........................

Just my disinterested .02.

Larry

[big mike71]

Originally Posted by ll____b0t____ll

First off as a forum staff person shouldnt you be following the rules of this site?
It is clear the OP has decided to use the braided hose and was seeking help with size NOT weather or not you think the product is worthwhile.
So by you posting to say what he wants to do with his truck is a waist of money with no facts to back up those claims as they are only "your" opinions and further by saying you expected to be flamed and expected arguments , doesnt that seem like maybe you just shouldnt have posted to begin with?
Sounds like baiting to me.
Just becouse you dont see the benifit in using a quality part as apposed to rubber hose and hose clamps doesnt mean others cant.

Everyone has a right to their own opinion but why discourage others from using a part that even though is more money holds more benifits?

And as far as the conditions under my hood , I replace whatever i can with billit alluminium and hoses with braided cuz i like to fix a thing just once.
And I didnt have to work for N.A.S.A or be a rocket scientist to figure that out.

It takes alot of nerve to take crap on longhorn man when your name is pink imo. Support the site.

[VanceH]

Originally Posted by big mike71

It takes alot of nerve to take crap on longhorn man when your name is pink imo. Support the site.

Love this board!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

[Jim_PA]

Originally Posted by Longhorn Man

if the conditions under your hood are anything close to what nasa deals with.... or nascar for that matter, then you have some bigger issues to deal with.
it's overkill.
i figured i'd get flamed... but expected better arguments than nasa.
that's not even apples to oranges.

The steel line rusts, and the stainless is too prone to breaking, and doesn't bend as nice.

[VanceH]

i figured i'd get flamed... but expected better arguments than nasa.
that's not even apples to oranges.[/QUOTE]


Did i ever tell you that i just love Oranges!!! Dont they use steel line from the factory?? I think mine is original and seems to hold up just fine? I am going to go with braided from the pump up, but thats only because Nascar requires it on my ride!!

[VanceH]

Hey Longhorn, my 67 sounds like a rocket ship!! Kinda same thing as NASA. I for one love your opinions!! Gives me things to think about. Keep up the great work!!

[Tx Firefighter]

I have a background (and even my college degree) in aircraft maintenance, so I'm pretty familiar with AN stuff. First and foremost, you will see AN hoses on aircraft just where a hose belongs, something that needs to bend and flex. If it's a straight run in a fixed position, they use hard line. I think what Andy tried to imply was that there is no reason to use AN hose between the carb and fuel pump. It's a fixed installation and not subject to movement. This is exactly why the OEM used a steel hard line in that application.

The argument was made that a hard line will deteriorate over time. This is true to an extent. But, AN hoses will deteriorate too. I spent many hours in my life rebuilding AN hose assemblies. We had to remove the end fittings and replace the hose itself. The FAA required this. The FAA did not require the hard lines throughout the aircraft to be replaced at intervals like the hoses were. I think this says something.

Further, braided will will absolutely kill anything it contacts with due to movement. You must secure it very well to keep it from rubbing anything else.

All said though, the OP may desire AN braided hoses in this application. I was just pointing out that there is some validity to what Andy was saying.

[Longhorn Man]

One of the main reasons we log onto a site like this one, is to learn. One man's opinion can be based on facts, or on speculation. The opinion I posted above, was based on facts.
I'll get back to my opinion here in a moment.
As far as the "baiting" comment... I'll assume you mean troll, since that is the closest thing in the rules to what you said. And the fact of the matter is, I was not trolling.
Also, I never said a single word about hose, clamps, nor NHRA rules. I said 3/8 inch steel fuel line.
Now, The reasons I even said anything about steel fuel line...
1. Cost.
Budget is almost always a concern. I can only assume it is in this case also, since he is doing it his self, and not paying a mechanic/restoration shop to do this.
2. Facts
Steel lines, while they do rust (after 40 or so years up under the hood) are in fact the preferred material for this application. As Keven pointed out, even in air craft, a steel line would be used in a fixed application.
3. education
With the questions asked by the original poster, I looked at it and saw he knows very little on the subject. When someone doesn't know, it is the our job (as forum members, and to an extent, friends) to assist in educating.

I have worked on heavy equipment pretty much my entire adult life. Trained in the army on M1-A1 tanks, M88 A1 recovery vehicles (70 ton and 56 ton full tracked vehicles) and all the way down to a little 1 1/4 ton hummer. In civilian life, I've bee working in a fleet and diesel shop, everything from escorts, to Mack/Volvo/freightliner/Kenworth tractors... plus some heavy off road equipment once in a while, D8 dozers, steam rollers, clear down to a little bob cat and small fork lifts.
M1-A1 tanks, happen to have a lot of steel braided lines. They are great, when they are needed. However, they don't just install steel braided lines from a pump to a pump driven item. It is only installed where flex is needed, on a high pressure line.
A stock fuel pump puts out what... 6, 7 PSI max? While I don't know a whole lot about the aftermarket mechanical fuel pumps, I doubt they put out much more than 12 or so PSI. So it is safe to say, braided line is overkill in that department.
Durability was mentioned... While a steel line is not good forever, I don't think it is a real concern... and, ad mentioned above, AN fittings, and the steel line its self, can, and does need some work over time.
Damage... Steel line won't damage ANYTHING under the hood. You bend it to shape, and if it is done right, then there is no damage caused to its self, nor any other component under the hood. Steel braided line on the other hand, if left resting on the thin inner fenderwell, can, and will actually rub a hole through the metal over time. Yes, it may take a few years of daily driving, but, the fact still remains, steel line can't do this. As a matter of fact, in many heavy duty/industrial applications, the steel braided lines will actually be covered with rubber, or even silicone type hoses, to protect everything else around it.

I could keep going on and on. I could point out how there is only one brand of aftermarket steel braided brake hoses (to my knowledge) that is DOT approved.... where rubber is the prefered material. Or point out how in factory applications, a short section of steel braided lines off the master cylinder in late model Chevy vans rub and cut through other lines in the engine compartment.
My entire point in this rebuttal, is not to 'one up' anyone, not to 'put the smack down' on anyone, not to 'troll'...
only to defend (with everything based off FACTS) and, to educate.

[my67chevytruck]

Curious what the consensus is in using aluminum vs. steel 3/8 tubing for the fuel line.

[Longhorn Man]

now you guys are gonna make me defend him...
supporting the site is great, but never required. This site always has been, and always will be a free site. Just becouse he is not a site supporter doesn't mean he can't have an opinion. If you want to defend me, cool, if anyone wants to defend him, that's cool too, but lets leave the supporter issue off the table. Non supporters are just as important as supporters.

[mclairmo]

I have had a Summit Racing braided fuel line kit with AN fittings installed from my fuel pump to my Holley 3310 carb since 1995 and had no problems. Never had to remove it, no leaks, no problems at all. I also ran new aluminum hard fuel line from my gas tank to the fuel pump, bending it myself by hand. Again, no problems since 1995. I also have never seen a hard steel fuel line (such as those used by the oem) crack or break in my life. Good luck.

[ll____b0t____ll]

I didnt really want to go public with this information but in light of taking some time to think about what I did in this thread I would like to publicly say I am sorry to long horn man.

Not a good excuse but I suffer from Bipolar Disorder and well I make a mess of things often for myself and with time looking back I feel I did you an unjustice and so Im sorry for the direspect I showed you here.

I hope you can maybe see past this and realize I am my own worst enemy but the person I want to be wishes I hadnt been such a jerk here.

So all I can do is say again im sorry longhornman for showing you disrepect , and sorry for hijacking this thread to do so but I needed to say it.

[big mike71]

Originally Posted by ll____b0t____ll

I didnt really want to go public with this information but in light of taking some time to think about what I did in this thread I would like to publicly say I am sorry to long horn man.

Not a good excuse but I suffer from Bipolar Disorder and well I make a mess of things often for myself and with time looking back I feel I did you an unjustice and so Im sorry for the direspect I showed you here.

I hope you can maybe see past this and realize I am my own worst enemy but the person I want to be wishes I hadnt been such a jerk here.

So all I can do is say again im sorry longhornman for showing you disrepect , and sorry for hijacking this thread to do so but I needed to say it.

It takes a big man to apologize, my wife has basically the same thing so I sympathize with you. She takes effexior it helps alot.

[C20-67_N_MO]

Well I for one have learn a lot of valueable information on fuel lines from this thread. And hope that others have as well in the process of some ruffled feathers.

Like LHM said the board is here for everyone to enjoy and learn every each other.

Just glad to be a part of it and hope to be here for years to come.

[Longhorn Man]

ll____b0t____ll...
First I have to say, thank you... but in reality, no apology needed.
It is a respectable trait to be able to say that, and in a public forum, even more so.
Everyone here butts heads from time to time. Some people just swallow it and deal with it in there head, and sometimes people vent it on here. It happens.
I personally never felt disrespected, nor offended, but I did feel you were calling me out, and I had to defend myself.
Again, thank you, I do appreciate it, most guys on here woulda let it fall off the radar, but you proved to be better than 'most' people.