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Geo Hahn
10-27-2014, 05:08 PM
I am going to use a TR6 (mechanical) oil pressure gauge on a non-TR British car (one that comes with a notoriously unreliable electronic sender and gauge).

Who can tell me what threads are on the back of the TR6 gauge for the oil line?

Also - I see the Moss catalog shows an adaptor from the block to the line (shown on this page (https://www.mossmotors.com/graphics/products/PDF/376-190.pdf)). Can someone tell me the threads that are on the block side of that adaptor?

I suspect that adaptor goes from BSPT to NPT but want to confirm to hopefully order the right bits the first time around. Thanks.

dklawson
10-28-2014, 08:37 AM
The original Smiths setup used a leather or fiber sealing washer between the gauge and a (more or less) straight threaded female fitting on the end of the oil tubing. Regardless of what the threads are both in the block and on the gauge, you will have no trouble using 1/8 NPT fittings to connect it. While you can use Teflon tape on the threads of the gauge before attaching the 1/8 NPT fitting, I prefer to use Teflon pipe dope instead. The tape can release threads of material that float around near the tiny hole supplying the gauge. Again, 1/8 NPT will be fine with some sealant on the threads.

The aftermarket gauge installation kits will come with some 1/8 NPT male and female compression fittings. The nylon tubing kits are OK for a few years but they can be delicate. There are also copper tubing gauge kits. They are nicer but for longest life you should loop the excess copper tubing into a coil between the engine and firewall to absorb vibration and engine movement. For a more permanent (and more expensive) hookup, Longacre sells 3 or 4 braided oil line kits at Summit Racing that are affordable. Visit Summit's web site and in the search field enter "Longacre gauge supply" to find the hose kits.

Geo Hahn
10-28-2014, 09:33 AM
Thanks. I have the TR6 gauge on its way (pretty good match for the other gauges in the car) and was thinking of this for the hose:

https://www.7ent.com/products/oil-pressure-gauge-hose-braided-stainless-steel-c-aht9.html

But I will check Summit & Longacre too.

PatGalvin
10-28-2014, 11:38 AM
Geo, Ted from TSI will make you a nice custom SS Braided Hose for this application. I have one for my TR3 that works great. Also, don't forget the little leather washer. My gauge leaked without it, no matter how much Teflon tape or pipe dope I used. Good luck!

Pat

dklawson
10-28-2014, 12:35 PM
Sorry to here your fittings leaked Pat. I have not had any problems using the NPT fittings and pipe sealant with Smiths gauges. The leather washer is a must if you are going to use the OEM type fittings. I am not sure if Seven has them to go along with the hose that Geo provided the link to. If they don't I believe someone on this board said Moss had them.

EDIT: I checked Moss. They have a number for the leather sealing washer but it is marked "NA". On the Seven web site they don't appear to have the seal either but they suggest using a nylon or soft metal washer in place of the original part.