Adapter Fitting for Smiths Oil Pressure Gage

CCX33911 · #1 (**permalink**) 04-29-2002, 09:32 AM

I am looking to adapt the Smiths Oil Pressure Gage to AN - 3 (aircraft). What is the standard Smiths fitting called? I assume that Earls or Aeroquip would have an adapter.

Thanks
Gary

Whaler · #2 (**permalink**) 04-29-2002, 10:33 AM

Assuming its a mechanical gage as it is a Smiths. I would assume its a Nut and ferrule for a 1/8 copper signal line. That goes onto a 1/8 tube to 1/8 pipe NPT pipe fitting. The engine may also be 1/4 pipe NPT so the fitting would need a reducer to go 1/4" to 1/8"

Just have to know the pipe/tube sizes

So i take it you will be replacing the original line with braided?

The gage end should be female 1/8" tube
engine will be the pipe to tube adapter in the same size too

Tim

CCX33911 · #3 (**permalink**) 04-29-2002, 11:24 AM

I am setting up the Oil adapter for 1/8" NPT and will buy a 1/8" NPT to AN-3 fitting from Earls. I will then run AN-3 braided line to the dash and hope to adapt to the Smiths gage.

The smiths gage has a fitting that looks like the end of a bolt with a center hole. The sealing surface is flat (like the end of a bolt). The line that comes with the gage has a nut and insert attached to the plastic hose. The insert (not sure what the real name is) is also flat and mates with the flat face on the gage. The nut just preloads everything.

Is this arrangement the "nut and ferrule" you were talking about? There is no tappered seat in the whole setup.

Whaler · #4 (**permalink**) 04-29-2002, 12:32 PM

Yes its a little different than what I expected. the nut and ferrule is separate from the 1/8 tube
You rely on the ferrule to bite the tube when the backing nut is screwed onto the gauge. Thus they are called compression fittings.
Yours sounds like a flat mating face with the backing nut used in the same way
Funny there's no bevel in the seal surface like in a female flare or compression fitting

I have Autometer "smiths replicas"

I guess you should just drag the gage with you into the speed shop

Sorry I couldn't help

Tim

Bob Putnam · #5 (**permalink**) 04-29-2002, 12:48 PM

The Smiths fitting is either BSP or proprietary. Try either MOMA (505-766-6661) or Nisonger (888-781-6968). Good luck...

ERA#569 · #6 (**permalink**) 04-29-2002, 08:58 PM

I have removed this reply . Scott

Andy FIA · #7 (**permalink**) 04-30-2002, 03:22 AM

CCX33911 - From the land of Smiths I can confirm that Bob is correct, the threads are 1/8" BSPP or BSP parallel.
You should really use the correct BSPP / AN fitting for this gauge, a female 1/8"NPT fitting will only screw onto the gauge a couple of threads before it galls on the brass.

Andy

ERA#569 · #8 (**permalink**) 04-30-2002, 03:18 PM

Gary, Andy FIA is correct DO NOT use the Pipe thread fitting. After a near disaster by screwing up the threads on a expensive Smiths gauge I remember now NOT using the pipe fitting. I crawed under the dash today to confirm. Thank God Andy FIA was here or else I would be buying you a gauge !
Sorry for the confusion, I just remember playing with that for days to get it right.

Thanks Andy FIA , Scott

Great Asp · #9 (**permalink**) 04-30-2002, 06:17 PM

Call Craig Hill at Top of the Hill Racing.
925-460-5297

He has a kit for this!

Great Asp

CCX33911 · #10 (**permalink**) 05-01-2002, 07:16 AM

Sorry for the delay in response. I actually ordered adaptor fittings from a vintage racer in CA. I will report back when I recieve the stuff and actually take a look. Asp: I did not see your post till this morning and had already order from the other guys. Thanks for the input!

Gary