AN fuel fittings for fuel system 8mm ~ 5/16th"

[DW SD]

Recently, I have been replacing much of my fuel system with AN fittings, in the interest of safety. Just got my fuel system up to pressure last night, in fact. I used a micrometer to measure the 8mm hard lines (conversion calculation yields the same results). They are .0024" (24 ten - thousands) larger than 5/16th". Not much. I bought Earl's slip compression fittings 5/16th" hard line to -6 AN. It worked like a charm. Just have to make sure the hard line was cleaned up very well (I used 320 wet dry sand paper). The fit is very tight for the compression nut and just right for the compression sleeve, itself. These are about $8 at street rod performance OR Summit.
BTW - I was concerned about running slip compression fittings and called tech support at Earl's to make sure they'd be safe at EFI pressures. They guarantee the fittings for 60 psi or less and intend them for fuel lines, including EFI.

Hope that helps!

Doug

[derkpitt]

Have you looked into using MS to AN union fittings?

The fittings in the photos look like they are for a flex hose.
Not for a hard line. The MS has a crush sleeve longer than the one used in the photo.

[DW SD]

No - do you have a photo or link?

[derkpitt]

http://www.gen-aircraft-fittings.com/template.asp?pagename=ftgs

[DW SD]

By the way, the fittings are not for a flex hose, though they do resemble the standard AN fittings (that's the point.) The brass sleeve is a crush fit onto the hard line.

To add to the resource, here's the page DerkPitt is suggestion: http://www.gen-aircraft-fittings.com/images/pdf/ftgflless.pdf (I believe). Yes, those look similar and would work, also.