Trying to identify oil pressure gauge thread

[sujitroy]

Years back when I got my Stag, the PO installed an oil pressure gauge. They had removed the oil pressure sensor. I went to a junkyard and got a tee from an MGB. (item no. 1 from left in photo) I then went to a hydraulic line shop and they made me a steel braided hydraulic line which I could plumb in. I'm not sure what the fittings on the ends are, but they gave me some adapters for the ends. (Item no. 4 from left in photo) One end of the adapter threads into the hydraulic line, and the other in an NPT. This threads in the oil transfer cover. The other adapter which came with the hydraulic line threads into the tee. The male threads on the tee are not NPT. The photo next to the tee went in the engine block of an MGB. The other end of this thing is not NPT either. Would anyone have a clue what the thread could be on the MGB tee?

The following may also give a clue. I bought a smiths oil pressure gauge. A pipe was included in the kit with some adapters. (The adapter is the third item to the left) One end of this supplied pipe will thread directly into the Tee of the MGB and the other end, threads onto the gauge. In the kit came some adapters which can change one end of this pipe to an NPT thread.

I just bought a new NPT tee and plan to reinstall the oil pressure gauge at the oil transfer cover., but I need to join the hydraulic line to the line which came with the gauge.


Sujit

[Phil S]

perhaps it would be best to take the lot into a hydraulic supply store, show them the threads needed on each end, block and gauge and let them puzzle it out

[marshman]

I rather suspect the threads are 1/8" BSP and not 1/8th NPT. BSP will be 28 tpi where as NPT is 27 tpi.

[sujitroy]

With shelter in place still here in California. I'm staying put else I would have made a trip to the shop which made the hydraulic line.

[roadster72]

Both those threads are likely to be 1/8 inch BSP. The MG experience forum says the oil port is 1/8"BSP. And that is the commonly used British thread on such cars..

[KOY 23]

If the Stag was an American designed car it would have NPT threads, as it’s British it has BSP. Or is that too simple?

[sujitroy]

If I'm not mistaken the oil transfer cover is NPT and that part is not American ha ha. Thanks to all. Her'e the problem as mentioned above, NPT is 27 tpi and BSP is 28 tpi. An NTP can thread into a BPS up to a certain point and then it binds. For gauges a few threads in and PTFE tape will work OK.
Generic pressure line kits in US sell for about $4 unlike the Smith's kits which are three times the price. The Smith line I'm sure I have has BSP at both ends. I'll hold off installing my gauge until I can go visit the local shop.

[Carboy0]

The thread on the original oil pressure switch sender is

1/8" x 27 NPTF

so the thread in the block is likely to be 1/8” x 27 NPT. When I bought my Stag it had a SunPro oil pressure gauge (US origin I think) the pressure hose ends also had 1/8” x 27 NPTF threads. Most UK gauges will have have British Standard Pipe (BSP) fittings.

[sujitroy]

Sorted out. The line which came with the gauge has both ends BSP. I just need a BSP to BSP coupler and can join my braided line to it. the other end of the braided line is npt.that will go into the engine via a npt tee.