What type of a fitting

dennis112 · Jun 23, 2007

is used to connect a 3an braided hose (female end) to an oil gauge that originally used a tube, a ferrel, and a small nut? The oil gauge has a male end that is maybe half the diameter of a 1/8" NPT fitting. I need to adapt it up to at least 1/8" in order to make a connection.

I have some brass fittings that came in the kit, but alas, none of them are small enough (less than 1/8" NPT) to screw onto the back of the gauge. What gives?????

D.Hearne · Jun 23, 2007

Have you tried a 1/8NPT fitting? I may be mistaken, but that's the smallest NPT size I know of. The line and ferule size is 1/16" on all the guages I've used.

1966ponyguy · Jun 23, 2007

NPT FYI

FYI, just for info sake, ( I agree it's probably a 1/8 NPT) but there is a 1/16 NPT size. some of the NOS jets use this size. If you need fittings for the 1/16 NPT, you will probably need to check with McMaster Carr or other industrual supply house for the taps or fittings.

dennis112 · Jun 24, 2007

1966ponyguy said:
FYI, just for info sake, ( I agree it's probably a 1/8 NPT) but there is a 1/16 NPT size. some of the NOS jets use this size. If you need fittings for the 1/16 NPT, you will probably need to check with McMaster Carr or other industrual supply house for the taps or fittings.

Thanks.

Yeah, I discovered that there is a 1/16" npt through google.

Unfortunately, after a little research, I discovered that the compression fitting used on the back of the gauge is a straight 5/16 x 24. There is no taper on either the back of the gauge or the fitting to make a firm, leak free connection.

I've done my McMaster Carr research and see nothing usable. At this point, I think I'm screwed in trying to connect this gauge. . . . . .

1966ponyguy · Jun 24, 2007

More 1/16 NPT info

The 1/16th NPT is the same as a 5/16 fine thread but with a slight taper. You still may have a 1/16 npt.

D.Hearne · Jun 24, 2007

All the oil gauges I've used had that same size fitting so you may be out of luck trying to use a -3an line for that. I use the plastic line and encase it in vacuum hose to protect and somewhat hide it in the engine bay.

dennis112 · Jun 24, 2007

1966ponyguy said:
The 1/16th NPT is the same as a 5/16 fine thread but with a slight taper. You still may have a 1/16 npt.

OH, WOW, COOL.

THANKS A MILLION!!!!

Rusty67 · Jun 24, 2007

You live anywhere near an Earl's supply ? I'm sure they could get it adapted eventually. It might look ugly with 9 fitings but they should be able to hook you up.

D.Hearne · Jun 24, 2007

Rusty67 said:
. It might look ugly with 9 fitings but they should be able to hook you up.

That sounds like some of the "adapting" I've done due to lack of the correct fitting on hand.

dennis112 · Jun 24, 2007

1/16NPT is 5/16" in diameter and has 27 threads per inch. My straight fitting is 5/16" in diameter and has 24 threads per inch. After looking around for a while, it looks like there are no conversion parts made to match them up. WTF up with that??????

So, I ended up making a 5/16 x 24 female to male 1/8" npt adapter on the lathe out of some brass. It uses a ferrel for sealing and a 1/2" long piece of 1/16" tubing to hold the ferrel straight while I tighten the the adapter to the back of the gauge.

I also built a test leak down test rig so I can check for leaks so I guess I've handled the problem the best that I can.

Thanks for all your help!

Rusty67 · Jun 24, 2007

dennis112 said:
1/16NPT is 5/16" in diameter and has 27 threads per inch. My straight fitting is 5/16" in diameter and has 24 threads per inch. After looking around for a while, it looks like there are no conversion parts made to match them up. WTF up with that??????

So, I ended up making a 5/16 x 24 female to male 1/8" npt adapter on the lathe out of some brass. It uses a ferrel for sealing and a 1/2" long piece of 1/16" tubing to hold the ferrel straight while I tighten the the adapter to the back of the gauge.

I also built a test leak down test rig so I can check for leaks so I guess I've handled the problem the best that I can.

Thanks for all your help!

Nice job, you punished that

What type of a fitting

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