Thread Sizes
Turbo Mini Forums

Does anyone know the sizes of the following threads please.

Mpi Oil Temp sensor
Mpi / Spi Water Temp sensor
and the thread in the block where the oil pressure gauge attaches to.

cheers

Eric T.

Team Racing

jimster

the thread in the block where the oil gage goes

is 1/8" BSP or it used to be on the pre A+

sorry about the others you asked about?

thats a start, thanks

Team Racing

i thought the new ones were 1/8th NPT?

otherwise the old a-series and a+ are bsp as ben said

All A+ blocks are NPT I believe...

Didn't know the MPi had an oil temp sensor?

Water temp sensor is a plain metric I'm sure - M10x1.5? Might be a coarse pitch metric though... Check it.

Yes I have wondered about the MPi oil temp sender. They definately have one as the dash has the three extra gauges in the middle of which one is oil temp.
Be interesting to find out where the sensor is located if anyone knows?

the oil temp sensor on an mpi is located just above the pressure relief valve, it's got a huge thread on it compared tp the oil and water temp senors

Team Racing

Have to take a measure

Knew at some point they went to NPT.

When i prep my block ill have to take some time figuring out whats what and make a list. (if i have time!)

Hope this enlightens you



NPT (national pipe thread) is the standard pipe thread in the USA.

FPT (FMPT) and MPT (MNPT) simply denote female or male. Virtually all the NPT threads that you will find are 'tapered'.
BSPT (British Standard Pipe Tapered) or BSPP (British Standard Pipe Parallel) are the common pipe threads used in the uk and also in Europe.

'Metric' is a broadly used term to describe threads used in europe

You rarely need an adapter because NPT fittings work just fine with BSPP or BSPT

You may have been told you should not mix BSPP with BSPT or with NPT you can ignore this crap in low pressure systems say under 100psi
you can often mix NPT fittings with BSPP or BSPT For example 1/2" NPT fittings work ok with 1/2" BSPP

In this case, you are mixing tapered with parallel, so use PTFE tape. the same is true for 1" NPT with 1" BSPP
Tapered vs Parallel Threads.

If you look at male NPT threads, you will notice the diameter of the fitting is tapered narrowest at the end.

Parallel threads do not have a taper. The most important thing to understand is that tapered threads form a seal differently than parallel threads.

Fittings with tapered threads seal on the threads. Use PTFE tape on these type of threads to help make a good seal.

Why does NPT work with BSPP?
1/2"NPT to 1/2"BSPP. Both have 14 threads per inch so they match up quite well. The primary difference is in the pitch (angle of the thread) which is 60? to 55?. Use a PTFE tape and they screw together and seal OK.

3/4"NPT works well with 3/4" BSPP as well since the threads per inch is the same, 14.

So on "LOW PRESSURE" systems these treads work ok,
In the past I have worked on pressures in excess of 36000 psi and normally of 2500 psi all day long.
With the old BRITISH STANDARD PIPE!

But there was no USA.... NPT stuff with the N.C.B in the seventies

suppose! the yanks have got to have their own veriation,
their own sizes.

Edited by BENROSS on 23rd Mar, 2005.

Good one ben!

That's the stuff that comes with experience ain't it... I stayed away from taper fittings purposely!

Just to confuse things further there are also the "JIC" range of pipe fittings, used mainly in motorsport, the threads are UNF sizes!

THANKS dave but i have been getting lazy for some time
pulled my socks up now buddy

i have also took the liberty of putting this on the FAQ section for all

When jims questions are answered, what thread size bolt do i need to block the top of the manifold off? The one that would normally be for a servo? Ive just used a hose with a bolt to get by with, and use the other takeoff for my dump valve.

Previous Engine: 1040cc Morespeed engine, 1275 turbo head T2 Turbo Mirage Manifolds Megajolt
Previous engine: STD metro turbo, megajolt
Drives: 399bananahp (flywheel) Honda Civic Vtec b18c4 T28 Turbo 1968 Mini

Megajolt maps to download: http://www.jamesfawcett.co.uk/cms/index.ph...&gid=3&Itemid=3

5/8 unf iirc

i used the bolt that goes in the end of the crank to block the servo take-off i think, think it was the pulley end one i used although not 100%.

minispares sell those sensors if anyone wants to look at them there are some pretty pictures in their catalogue

ok this is the puppy,
http://www.minispares.com/Product.aspx?pid=32602
my one is about 50 miles away so I can't measure it

Team Racing

So why do you want to know the thread of this? You using an MPi block? Or that sensor? It looks huge - I wouldn't fancy trying to tap that hole by hand... (or paying for a tap)

I've had a re think since then, I'm going to use a water temp sensor instead

Team Racing