Oil lines - what standard are they?

[Gordie Allen]

I have a 4104 with a 670 in it. I've got some oil lines to replace. Are these "an" fittings? I can't find a local source and I don't want to buy the wrong thing. I know "an" was developed during WWII and the 670 preceded WWII, so I'm just checking.

[luvrbus]

Most DD used JIC 37 degree fitting or SAE

[Gordie Allen]

Clifford,
So do you know if -an and JIC have the same thread pitch?

[thomasinnv]

The thread is not what makes the difference, it is the angle on the flare. Jic are 37° and sae are 45°. They may or may not have the same thread pitch depending on where it was made.

[chessie4905]

SAE nuts are sometimes marked if you look closely.

[Debo]

Every once in a while, one of mine will look suspect or start leaking. As that's happening, I've been replacing mine with AN fittings and hoses from summitracing.com.

I used to travel in the aviation world, and I understand them more, plus they're widely available online at these speed shops like Summit. Just my way of doing it...

[Jim Eh.]

"AN" stands for Army/Navy. It is more a performance spec than a thread pitch or flare design but is considered 37 degree as is an SAE flare. It was done to standardize aircraft fittings. Today's "AN" are for the most part not true AN fittings just the internet equivalent. Just try pricing out a true AN fitting for an aircraft and you will soon find the $3.49 Ebay fitting should cost $50.49

[luvrbus]

Don't the true AN have a taper to the threads I know they are pricey I had to buy a few for my helicopter kit that were missing

[c-coop]

the original fittings on 2 stroke detroits  are inverted flare    the hose end has a flare with a male threaded nut on it