oil pipe fitting size variation button to gauge

[JonE]

I'm trying to fit a later test device to diagnose the oil button on a 1929/30. 
But the fittings are different - the later oil gauge has a smaller male connector.
Is there an adaptor sold that someone else has searched for and found, please?

[Ruairidh Dunford]

Probably just as cheap and easy to make up another pipe with the later connections Jon.

[JonE]

thankyou R.
So is this the size that fits the rear of the needled oil gauge, or the one that fits the block? and which size is t'other! https://www.theaustinsevenworkshop.com/p...older-type

[Ruairidh Dunford]

That should fit the standard oil pipe take-off in the crankcase.

You will need to check the oil gauge you have to be certain about the thread on it.

[Austin in the Shed]

What are you trying to diagnose with the oil button Jon ?
The button should lift off the seat at about 2-3 psi,half way out about 5 and full out 7-10 if it works.
The Smiths gauges are usually 1/8 bsp with a flat seat,Others could be anything.

[JonE]

Hi. Car runs fine. Oil button doesn't "lift", but have removed to check (I'm just getting engine running so need security of knowing its working!) and the spring/suction seems/feels fine.

I've bought two old gauges - one I think a Harcourt like those on austin 7 dashes - and they both appear to be same male connector... which is smaller than the male connector on the block.

I'm a bit confused as the "bigger one" (the one on the A7W website) is referrred to as 1/8 BSP too - is that just the thread itself? I want to know what determines the brass "nut" size!

[Colin Wilks]

Hi Jon,

If you take all the bits into a hydraulic hose shop I would expect them to have adaptors on the shelf to step from the probable metric or UNF thread on your test gauge to the BSP thread on the back of the oil button. The pressures you are testing are very low so a brazed up special would do the job if needed and shouldn't cost more than a few quid.

Colin

Ps you can check BSP thread sizes here:
https://www.amesweb.info/Screws/British-...-BSPP.aspx

[Ruairidh Dunford]

Hi Jon,

1/8 BSP is the thread and that is correct for the crankcase union and an 'A7' Harcourt oil gauge - see below.

   

   

   

   


The union nuts come in various external sizes - choose the one you prefer.

[JonE]

ok, thankyou... but how would one define the photographed one if you you had to explain its spec to someone? How would others classify them as parts?

the O/D of the stud bit, or the Across Flats dimension?

[AustinWood]

I believe BSP is specified by pipe bore, 1/8" in this case.
The spec can be found on the internet.