Topic: Oil pressure switch - whats the thread dimensions?

[flybackwards]

Does not fit my metric thread gauge? whats the thread on the switch - looks like 10mm something? Thanks to the hive mind...

[bryanj]

Dont think its metric, might be NPT but dont quote me on that

[71 V12]

I also think it’s 1/8 National Pipe Thread NPT.

[flybackwards]

Thanks - that never occurred to me - I'll try my box of plumbing parts!

[BenelliSEI]

I also think it’s 1/8 National Pipe Thread NPT.

Correct. +1

[Don R]

 1/8" pipe taper was extremely tight on mine but did thread in. In the pipefitting trade I've seen some european pipe that didn't have the taper the same as npt, I wondered if that is the case.   

[Deltarider]

Just don't be tempted to screw it all down. It is not necessary.

[slikwilli420]

Is 1/8 BSPT. I have used adapters for oil pressure sending units multiple times. This is the correct thread.

[Bodi]

1/8 NPT will kinda work but it will jam and probably damage the case threads. 1/8 BSPT is 27tpi and 1/8 NPT is 28tpi, plus the taper angle and thread form are also different. Adapters are not hard to find if you want an NPT switch or other fitting. But they are close enough that screwing it in with teflon tape should work ok in a pinch... but that's still wrong.

[dusterdude]

If you want an adapter,plews-edelman makes one

Sent from my LM-X420 using Tapatalk

[tlbranth]

It's a British pipe thread which is 1 thread/inch different from US pipe thread

[flybackwards]

Who knew it could get this interesting -

So it will be an interesting adaptor - bspt male to go into the oil gallery - one us 1/8 npt female for my autometer pressure sensor and one bspt female for the honda pressure sensor. Or I could just go m20 x 1.5 to 1/8 npt off the gallery end plug and leave the other well enough alone - don't like leaving the fittings out in the breeze though. Maybe I need to get a piece of brass and some taps and start machining.

[bryanj]

Have you made sure there is room for all this extra hardware? There isnt on a 500

[flybackwards]

I'm pretty sure it will fit ok - the pressure switch on the 750 comes out on a slight angle to the rear so the cylinder fins have good clearance.

I found what I need on Amazon - its called a turbo adaptor - used by turbo guys to steal the turbo oil supply from the oil pressure switch feed.

Various flavours available - I found one which is a piece of stainless hex bar stock through drilled with a bspt 1/8 male on one end a bspt female on the other and a 1/8 npt on the side. Replace the pressure switch with the adaptor - put the pressure switch on the top end and you have a 1/8 npt on the side for whatever purpose you have in mind.

Just in case anyone else wants to know...

[bryanj]

If all you need is a pressure guage why not drill and tap the gallery end cap by the points plate

[flybackwards]

Thought of that but don't like pieces hanging out in the breeze, actually Joker machine makes a nice gauge assembly to fit that cap - but since they never have anything in stock you can't get it without waiting months. Just too picky I guess! I'll put up a picture when its all done and dusted.