I got my AEM fuel rail for awhile and never got to install it as I was planning to change the fuel lines to braided hoses and -AN fittings for looks.
When I finally decided to go ahead with the project, I tried to search for the size of the fitting I will need. During my search, I stumbled upon a article by Precision Engine on AN fittings which I found to be one of the most comprehensive available. An article in Honda Tuning May 2008 issue alsoexplained quite extensively on AN fittings.
Do read up if u intent to upgrade your fuel hose and fittings for more bling factor :)
Anyway, just a quick write-up until I come up with a post on fuel line and fittings "upgrade" for the EG. The AN (Army/Navy) sizes originated from the Aerospace industry years ago and were designated as the Outer Diameter of the rigid metal tube that each size fitting is used with. For hoses it will be the measurement of the Inner Diameter, where it is measure in denominations of 1/16″ of an inch. For example, a -10 size translates to 10/16″, or 5/8″ inside diameter and -6 means that the inside diameter is 6/16″ (or 3/8″). A -8 size is 8/16″ (or 1/2″) inside diameter. Just remember that the format is based on 1/16″.
Important note: The AN fitting features a 37 degrees flare while home plumbing are using 45 degrees flare. THIS MEANS they do not fit each other!
Standard thread size for AN fittings (not to be confuse with hose size).
For AEM fuel rails, the end fittings are AN6 or 9/16"-18 (9/16" is the 'bore' size -18 is the thread per inch (TPI)).
Basically, when all the hoses and fittings are in -AN sizes, it is really easy to match the fittings to the hoses. A -6 hose will match a -6 fitting. The problem arises when u need to get the right adapter for match the NPT, METRIC, BSPT size. For the EG, most parts are in Metric size. For example the stock fuel rail is apparently M12x1.5 (Yet to be confirmed), so u will need to get a M12 x 1.5 to AN -6 adapter.
BTW AN fittings aint cheap, so do make you get the right size before ordering. Replacing the fuel line from my two external fuel pump to the fuel rail will cost me in the excess of US$100 excluding shipping cost.