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If you want to separate yourself and your car from the amateurs you have to stop using cheap rubber hose and clamps to plumb the vital fluids to your motor. That stuff works and gets you by, but it is not classy and has major limitations in durability and more importantly, safety. Most racing bodies, like the NHRA, do not allow more than a six inch stretch of rubber hose for things like fuel and oil lines. They mandate that those fluids flow through hard-line or steel braided line as those two materials are unlikely to burst, melt, or be cut in the event of a mishap. That is why the top race cars at the track have motors decked out in steel braided line and those spiffy red and blue fittings - it is due to safety and durability, not just because it looks cool. The greatest benefit to AN (pronounce each letter) is in the sealing capability. A connection between male and female AN flares can handle tremendous pressure without leaking, making it the right choice for oil, fuel or water. In this article we'll give you the entire scoop on how to properly plumb your car with AN hard and soft line.

AN stands for "Air Force-Navy Aeronautical Standard" and was an aviation fitting standard developed around WWII. The fitting featured a 37 degree mating angle which provided superior sealing compared to the common 45 degree fittings. The fittings also utilized a higher class of
3 key facts about AN fittings.
Flare angle is 37°, not 45°
Interchangeable with JIC fittings
Divide AN # by 16 to get inches
thread quality. Eventually the AN fittings saw widespread military use and a multiple manufacturers began producing the fittings, leading to quality problems. The Joint Industries Council (JIC), an industry organization, sought to standardize the specifications on this type of fitting and created the "JIC" fitting standard, a 37 degree fitting with a slightly lower class of thread quality than the military AN version. The SAE went on to adopt the JIC standard as well. As a result JIC or SAE 37 degree fittings are perfectly interchangeable with AN fittings, and while this may not be acceptable for military aviation use, for automotive use there is no downside other than perhaps mismatched color coordination as JIC fittings are not available in the pretty anodize aluminum colors. However this may be a worthy tradeoff considering the JIC fittings are a fraction of the price of their true "AN" counterparts. We mixed and matched in this article to show you their interchangeability.

Using AN
A half-dozen companies make AN fittings, hose, and line and most all of it is interchangeable except for certain proprietary "push on" type hoses and fittings. Always check the manufacturers information before purchasing hose or hose ends to make sure it is compatible. The AN side will always be 37°, it is the hose side that can vary depending on manufacturer designs. AN components come in easy to understand sizes, all divisible by 16 for easy conversion into fractions of one inch. For example, a -8AN (dash 8 AN) hose is 8/16" inner diameter, or 1/2" inch. AN is generally available in -4 to -12, and larger specialty sizes.

When selecting AN you must determine if you need to use hard line or soft line (generally Teflon, rubber, or special material with a steel braided or other protective sheath) or a combination of both. Hard line is not specific to AN, and this can be aluminum or steel and can be sourced from any hardware supply store. In other words 1/2" aluminum tubing is compatible with -8AN fittings. Soft line is AN specific because it needs to mate properly with the hose ends (as we'll show you later in this article.) When selecting soft line be sure to use hose material that is compatible with the fluid and pressure you plan to run through it.

(Flaring the Hard Line)
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In This Article:
Pop the hood on any serious race car and you'll likely see beautiful steel braided line and colorful fittings. As nice as the look this is all about functionality and safety. In this article we cover how to properly source, flare and assemble AN fittings and lines.

Despite being initially developed for military aircraft use, AN has become a niche industry in the automotive performance market. Companies like Russell, Earls, and Aeroquip all produce a huge variety of fittings, hose ends, and hose products to plumb any automotive fluid.

It is important to distinguish the difference between an AN/JIC flare and a typical compression flare. While the look similar, the two hard lines have different flare angles. Left is a 37° flare used for AN/JIC, while right is 45°.

Using a 45° flared hardline on an -AN fittings will result in leaks. The paint pattern here shows incomplete contact between the male and female ends.

Here we see the result of a proper seal between the AN fitting and 37 degree hard tube flare. This seal will not leak and requires no sealant or Teflon tape to work.


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