ausmini :: View topic - Water temp sender thread size

OK...
The thread for the oil sender in block is called 1/8-28 BSP. It is a pipe thread, so the size `1/8' is actually for what the pipe would be (inside).
It does measure around 3/8" diameter, but is not a 3/8 thread.
a 1/8-27 NPT adapter will screw in pretty well, but it is very slightly too big. Will work OK.

The temp sender in head is either 5/8-16 (UNS bastard thread) or 5/8-18 UNF (depending who you talk to).
All I can say is, a 5/8-18 UNF tap cleans it out properly without removing metal so IMO it's close enough. AND, you can buy them...

The temp sender in head is either 5/8-16 (UNS bastard thread) or 5/8-18 UNF (depending who you talk to).

Does anyone know what the thread / size is for a water temp sender unit in a mini head?

I'm fitting a speco elec water temp and need to buy an adapter. Their parts cat. has these listed - will one of these work?

adaptor 543-31
1/8 NPT x 1/8” BSP elec water temp
adaptor 543-32
1/8 NPT x 3/8” NPT elec water temp
adaptor 543-33
1/8 NPT x 1/2” NPT elec water temp
adaptor 543-34
1/8 NPT x 5/8” UNF elec water temp

The elec oil pressure sender screwed straight into the block - I was suprised, and happy about that one!

Cheers, Tom.

Author:	minivanman [ Sat Aug 04, 2007 1:48 pm ]
Post subject:	Water temp sender thread size
Does anyone know what the thread / size is for a water temp sender unit in a mini head? I'm fitting a speco elec water temp and need to buy an adapter. Their parts cat. has these listed - will one of these work? adaptor 543-31 1/8 NPT x 1/8” BSP elec water temp adaptor 543-32 1/8 NPT x 3/8” NPT elec water temp adaptor 543-33 1/8 NPT x 1/2” NPT elec water temp adaptor 543-34 1/8 NPT x 5/8” UNF elec water temp The elec oil pressure sender screwed straight into the block - I was suprised, and happy about that one! Cheers, Tom.

Author:	Mick [ Sat Aug 04, 2007 2:03 pm ]
Post subject:
This was asked last year and came up on a search straight away, althought the stuff you have pasted in looks more like the oil pressure adaptor thread: DrMini wrote: OK... The thread for the oil sender in block is called 1/8-28 BSP. It is a pipe thread, so the size `1/8' is actually for what the pipe would be (inside). It does measure around 3/8" diameter, but is not a 3/8 thread. a 1/8-27 NPT adapter will screw in pretty well, but it is very slightly too big. Will work OK. The temp sender in head is either 5/8-16 (UNS bastard thread) or 5/8-18 UNF (depending who you talk to). All I can say is, a 5/8-18 UNF tap cleans it out properly without removing metal so IMO it's close enough. AND, you can buy them...

Author:	minivanman [ Sat Aug 04, 2007 3:02 pm ]
Post subject:
This is the whole list: I think both senders are the same thread - the oil came with an adapter, and the water temp sender screws into it, but the adapater is also too small (external). I've got electric water and oil. So the internal is 1/8 and the external is either 3/8NPT, 1/2NPT or 5/8UNF if any of their adapters work. They're a common gauge, so if anyone knows 100%, would be greatly appreciated. This is their complete adapter list: adaptor 543-31 1/8 NPT x 1/8” BSP elec water temp adaptor 543-32 1/8 NPT x 3/8” NPT elec water temp adaptor 543-33 1/8 NPT x 1/2” NPT elec water temp adaptor 543-34 1/8 NPT x 5/8” UNF elec water temp adaptor 542-21 1/8 NPT x M14-1.5 elec oil gauge adaptor 542-22 1/8 NPT x M16-1.5 elec oil gauge adaptor 542-23 1/8 NPT x M18-1.5 elec oil gauge adaptor 542-24 1/8 NPT x M12-1.5 elec oil gauge adaptor 542-25 1/8 NPT x 1/4 NPT elec oil gauge adaptor 544-41 5/8 UNF x M16-1.5 mech water temp adaptor 544-42 5/8 UNF x M18-1.5 mech water temp adaptor 544-43 5/8 UNF x 1/2” NPT Holden adaptor 6/V8 & SB Chev 544-44 5/8 UNF x 3/8” NPT Ford & Chrysler V8 adaptor 544-45 5/8 UNF x 5/8 UNF fitted with O ring seal

Author:	Mick [ Sat Aug 04, 2007 5:06 pm ]
Post subject:
Here it is again: Quote: The temp sender in head is either 5/8-16 (UNS bastard thread) or 5/8-18 UNF (depending who you talk to).

Author:	steve1965 [ Sat Aug 04, 2007 5:26 pm ]
Post subject:	Re: Water temp sender thread size
minivanman wrote: Does anyone know what the thread / size is for a water temp sender unit in a mini head? I'm fitting a speco elec water temp and need to buy an adapter. Their parts cat. has these listed - will one of these work? adaptor 543-31 1/8 NPT x 1/8” BSP elec water temp adaptor 543-32 1/8 NPT x 3/8” NPT elec water temp adaptor 543-33 1/8 NPT x 1/2” NPT elec water temp adaptor 543-34 1/8 NPT x 5/8” UNF elec water temp The elec oil pressure sender screwed straight into the block - I was suprised, and happy about that one! Cheers, Tom. Can't you use the original one they came with the engine. Steve

ausmini https://www.ausmini.com/forums/

Water temp sender thread size https://www.ausmini.com/forums/viewtopic.php?f=2&t=34489	Page 1 of 1

Author:	minivanman [ Sat Aug 04, 2007 10:41 pm ]
Post subject:
Sorry Mick, don't know much about threads - just worked out, is the 16 / 18 the number of threads / rounds per 10mm or something etc - I was thinking it was diameter at first. I'll look into the 1/8 NPT x 5/8” UNF elec water temp adaptor 542-21 and see what happens. Was simply trying to get a 100% answer on the size / thread before purchase. As I said, they're a common gauge and I think some mini people would of fitted them. Don't like the idea of tapping threads in heads if I don't have too. I have an external pipe threader, might have to mod / make an adapter then. steve1965 - haven't checked - I guess they work on resistance to temp ratio. Will stick them on the stove and meter / compare at alt temps if I have to.

Author:	drmini in aust [ Sun Aug 05, 2007 7:28 am ]
Post subject:
5/8 -18 UNF is 18 threads per inch. Trust me these fit, you will not buy a 5/8-16 one- 5/8-16 is an orphan thread.

Author:	minivanman [ Sun Aug 05, 2007 11:38 am ]
Post subject:
Cheers Doc, now armed with enough info to chase one down on Monday.

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