AN (Army-Navy) fittings size by the OD of the tube they fit, measured in 1/16" increments. AN-6 means 6/16" = 3/8" tube OD. The thread on the fitting end is a 37° JIC flare; the port end (ORB) is straight-thread with an O-ring.
AN size chart
| AN Size | Tube OD | JIC Thread | ORB Thread |
|---|---|---|---|
| AN-3 | 3/16" | 3/8-24 | 3/8-24 |
| AN-4 | 1/4" | 7/16-20 | 7/16-20 |
| AN-6 | 3/8" | 9/16-18 | 9/16-18 |
| AN-8 | 1/2" | 3/4-16 | 3/4-16 |
| AN-10 | 5/8" | 7/8-14 | 7/8-14 |
| AN-12 | 3/4" | 1 1/16-12 | 1 1/16-12 |
| AN-16 | 1" | 1 5/16-12 | 1 5/16-12 |
Sizing by application
- EFI fuel feed (street): AN-6
- EFI fuel return: AN-6
- High-flow fuel feed (500+ HP): AN-8 or AN-10
- Oil cooler: AN-10 or AN-12
- Turbo oil feed: AN-4 (restrictor recommended)
- Turbo oil drain: AN-10 minimum (gravity, low pressure)
- Coolant lines: AN-16 or larger