Hi Guys

I am currently installing a VDO machinical temp gauge and am woundering what is the adapter that I will need (since the is a s&*tload of them listed?)

The gauge comes with a 1/8" -27NPTF fitting as standard.....but you can buy the following adapters
1/4" -18NPTF
3/8" -18NPTF
5/8" -18UNF
1/2" -14NPTF

Any ideas???

Also want to install a oil pressure warning light switch and need to know the thead size for the oil pressure gauge in order to buy a T adapter. The following sizes are available
1/8" -27NPTF
1/4" -18NPTF
1/8" -28BSPT

Again any ideas

Also what pressure would you buy???
21Kpa or
55Kpa


Minimad

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You can take the boy out of the racer.........but not the racer out of the boy!

The water temperature sender is 1/2 inch. I've got one here with a vernier as well.

I'm not close enough to a oil sender to get a measurement.

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SooperDooperMiniCooperExpertEngineering

All garage work involves equal measures of enthusiasm, ingenuity and a fair degree of irresponsibility.

If you are running an oil pressure gauge you should run the higher pressure light switch. The theory is that if the oil pressure drops a little the light will come on and you can watch the gauge before any damage is done.
If you run the lower pressure light switch you may find that the damage is done before you even look at the gauge.

A long while ago I rebuilt the engine in my 1275LS. When I was out running-in the motor one of the brand new oil cooler hoses blew off the cooler. The light came on and I looked at the gauge and it was dropping very quickly so I shut the motor off before the pressure had hit the bottom. If I had been running the standard light switch the light would have come on near zero.

Sorry I can't help with the thread sizes.

Best I could get on the Oil pressure gauge in the carpark was 3/8". That was using the small amount of thread exposed outside my oil pressure T-piece and the verniers.

I can't take it out as I don't have the tools and I'm not in my mini working clothes.

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SooperDooperMiniCooperExpertEngineering

All garage work involves equal measures of enthusiasm, ingenuity and a fair degree of irresponsibility.

Thanks guys...The higher pressure wwitch sound like a good idea...the only thing is that it will probably be on at hot idle!!!....but it is a race car

Minimad

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You can take the boy out of the racer.........but not the racer out of the boy!

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...

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

Thanks Doc, I was wondering as to why they were offering 1/8 adaptors..


But I don't understand the 5/8UNF tap for the head. The one I have here definitely measures 1/2" accross he thread(or just under 13mm. Is there something strange going on like the oil pressure adaptor?

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SooperDooperMiniCooperExpertEngineering

All garage work involves equal measures of enthusiasm, ingenuity and a fair degree of irresponsibility.

Is there an adaptor in the head for that to screw into- 1/2" was a popular size for some (other) cars...
all A series heads (that have the tapped hole) have the 5/8". Definitely.
But our 850 and 998 Deluxe in the 60s had NO threaded hole.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

Not this head, it's a standard head fitted to a 998 clubman.



The sender is a standard Smiths (It's stamped on the side).

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SooperDooperMiniCooperExpertEngineering

All garage work involves equal measures of enthusiasm, ingenuity and a fair degree of irresponsibility.

As usual I can rely on the doc and everybody else...thanks

So it sounds like the oil pressure switch adaptor that I need is

1/8" -28BSPT (Male) (motor)
1/8" -28BSPT (female) (oil pressure gauge)
1/8" -27NPTF (female) (oil pressure switch)

For those interested........ VDO part Number 230.036 (66mm long)

AND water adapter 5/8" -18UNF (external thread) to 1/8" -27NPTF (internal thread)
VDO Part No. 320.052

Now pressure switch for 1/8" -28BSPT can be either ????
55 Kpa (8PSI) VDO Part No 231.083 or
21 kpa (3PSI) VDO Part No 231.082

I would suspect the 8PSI one would be the best

Minimad

Ps I borrowes the VDO book from my local parts store overnight

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You can take the boy out of the racer.........but not the racer out of the boy!

Oh Crap!!!!

The neigbour just loaned me a nifty little thingy that you can measure the "treads per Inch'

Aparently...the Smiths machinical oil pressure gauge that I run has a 1/8" -27NTP in the block. The 28 TPI just wont go

Sooo ...since the 1/8" -27NTP seems to fit so well. I will just order the t adapter with 3 of these (VDO Part No 230.031)

The water 5/8" -18UNF seems right

Will let you know how the fitting goes

Minimad

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You can take the boy out of the racer.........but not the racer out of the boy!

where do you tap the oil pressure switch?

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1975 Leyland Clubman 'S'
1976 Leyland Clubman 'S' *work in progress*
I smile everytime!

It should be allready be there just above and to the left of the distributor underneath the oil pipe to the filter.

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SooperDooperMiniCooperExpertEngineering

All garage work involves equal measures of enthusiasm, ingenuity and a fair degree of irresponsibility.

A bit of info on threads etc.

This is a BRITISH car. It doesn't like American threads! Remember the Boston Tea party!

Anything with BSP or BSPT is a BRITISH thread and your Mini will like this.
BSP is a Whitworth form thread (55 deg thread angle) used for joining pipes and other bits containing liquids, gases etc..

Anything with NPT or NPTT is an American thread. Your mini will not like this.
NPT is the American standard (60 deg thread angle) used for joining US pipes.

Anything with UNF or UNC is a politically correct thread (60 deg thread angle) with a bit of each thread system, that came out of this thread stuffup by our American friends insisting on having their own thread system, different to everyone else. Well at least different to the British Empire, (but then there's also the French). Boston Tea party again?

During the 2nd world war it was found that even though they were on the same side, the threads on bolts etc couldn't be interchanged so spares from one side of the Atlantic didn't necessarily fit spares from the other side. Solution - come up with a common thread that every one would use. Result was the Unified thread system. UNC, UNF, UNEF etc.
However the British continued to use the British standard for pipe threads, BSP, BSPT etc and the Americans the NPT or NPTT pipe threads.

I think the British had one win as US built Rolls Royce Merlin engines made by Packard? continued to use British threads.

The Mini oil take off point for pressure switch or gauge is 1/8" BSP 28 TPI. It is not BSPT (T=tapered thread or pipe sealing thread). However you can use a 1/8" BSPT 28 TPI fitting as they both have the same number of TPI. The 1/8" NPT thread is 27 TPI but since it has such a short engagement length you can usually find that it will fit and not leak. A bit of thread sealant can be used if necessary.

The temp transmitter thread in the head is 5/8" UNF 18 TPI. Some heads don't have a tapped hole in the head (850's etc) but some had a tapped hole in the thermostat housing. Not sure of this thread but probably the same 5/8" UNF.

A bit of warning here about using the oft mentioned 5/8" 16 TPI UNS thread tap offered by Minimania etc for repairing the thread in the ends of the Mini crankshaft. (UNS = Unified Special) It is NOT the correct thread form. It is a more readily available constant pitch thread tap (same TPI irrespective of diameter) but it has the wrong thread angle (60 deg not 55 deg)
The Mini (and a lot of other BMC engines) use a bastard Whitworth form thread of 5/8" 16 TPI WHITWORTH (55 deg thread angle). The UNS tap will go in but it will cut away some of the thread form. Not a good idea for this highly stressed thread. BMC provided a special tool number for this tap - 18GA03. See section s-2 of the OZ Mini Workshop Manual TP832.
The thread on the end of the camshaft is also a bastard thread but not sure what this one is.

Most other threads are UNC or UNF.

Some Lucas electrical bits have BSF (British Standard Fine - Whitworth equivalent of UNF) or BA (British Association) threads so be careful.

As an aside the BA thread system is a Metric system and its British!

I'll get off my soapbox now.

Hope this helps
RonR

Thanks for all of that

I have ordered 1/8" -27NTP oil fitting as they are easy to get hold of

They arrive tommorrow....so lets see

Minimad

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You can take the boy out of the racer.........but not the racer out of the boy!