oil pipe fitting size variation button to gauge

[Ruairidh Dunford]

I will phone you...

[Tony Betts]

Hight of Union nut, is usually described the same as they would a helicoyle etc.

Thread x diameter.

So If you buy 1D the hight of the Union nut will be the same as the width of the thread.

If you ever buy helicoyles buy them 1 1/2D. After that the thread does nothing for strength.

Hope it helps.

Tony.

[Austin in the Shed]

I don't wish to complicate things but BSP threads are available in parallel and tapered.ie the grease nipples will be BSPT but all the pipe fittings will be parallel.

[JonE]

All understood now. I became confused as there seem to be two spannering sizes of retainer nuts for the same nipple.
For others in my situation, the pre-oil gauge buttons have a coarser thread. I'm going to simplify the whole run and change over the button to gauge permanently as my dash is not original.

Was a 29/30 bulkhead just grommeted for a single run from block to button.. or was there a pipe joint at the bulkhead?

and where approximately does it penetrate the bulkhead?

[Austin in the Shed]

The oil button thread is 1/4 BSP (Parallel)

[Chris Garner]

Single run, Jon. No joint.
Chris

[Colin Wilks]

Descriptions:

The thread on the back of the button is a 1/8” BSP Parallel male and seals on the internal cone.

The adaptor is a “-02” (dash 2) ⅛ BSPP male to ⅛ BSPP male (not BSP Taper, which seals by an interference fit between male and female threads). Again the seal is obtained on the internal cones, although new fittings with good straight hex faces will seal on dowty washers if screwed into a port.

As I said before you can check the BSP specs here: https://www.amesweb.info/Screws/British-...-BSPP.aspx

If these fittings are ⅛ BSPP they will measure 9.728 mm across the thread with 28 threads per inch, if 1/4 BSPP
13.157 mm and 19 tpi.

[JonE]

Thanks for all the advices. I'm going to keep simple and save weight by abolishing all the present joints and just using my newly acquired, self-renovated manky Harcourt gauge for a permanent fixture. (I really want to use the other snazzy aircraft gauge which also has 1.8BSP fitting, but its bigger and heavier and I don't want the car to get too much attention from bean counters... or to gain pounds)

[Chris Garner]

Jon,
I think you're confusing beans with rivets!
Goodness, that Harcourt is manky.