just did a bit of research and it shows the smiths gauges with 90 deg F in the middle

Slacko,

Maybe you mean 90 deg C?! Because 90 F is only 32 degrees C!

M

_________________
67 Deluxe
Dry suspension
1293cc, 11:1 comp, RE 282 camshaft, 45 Weber, extractors etc
4 synchro close ratio gbox
Cooper S brakes, no booster
Stealth box, as Doc says "goes harder and idles!"
RH tank cos I needed it crossing the Nullarbor etc..

In my experience every gauge I have seen has the thermostat setting more or less right in the middle of the gauge, so I think its safe to assume that when its properly warmed up the needle should sit in the middle.

Surely the needle position would depend on what temp thermostat is fitted? Or are you suggesting a suitable thermostat should be installed to achieve a N temp indication on the gauge under normal running conditions?
I would really like to know what the ideal engine coolant temp should be in normal conditions and what a good gauge should indicate...

_________________
67 Deluxe
Dry suspension
1293cc, 11:1 comp, RE 282 camshaft, 45 Weber, extractors etc
4 synchro close ratio gbox
Cooper S brakes, no booster
Stealth box, as Doc says "goes harder and idles!"
RH tank cos I needed it crossing the Nullarbor etc..

I now use an 82C thermostat because a 74C didn't warm my toes in Winter.
My gauge sits bang in the middle except on the freeway where it runs cooler due to the matic heater = aux radiator.

_________________
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.

Specs from the workshop manual re: thermostat state starts to open at 82°C so that would be around the mid point of the gauge....certainly I changed my thermostat and the needle sat in the middle.
I'm generalising of course but an Astra and a Landrover and a Mazda (and a mini) were the same. Needle sits in the middle..After a while thermostats start to open earlier so I change them when the gauge tells me it's not warming up properly.
I'm not sure why some would wish to fiddle with the specs of the thermostat, the idea is to get the engine hot enough to evaporate water to prevent corrosion and acid buildup...

Sometimes you need to...all engines are not the same so far as the amount of crud in their water jackets and or their ability to clear or soak heat...

A good one was the 1976 HX Holden 6 cylinder lemon engine...in order to meet emission "standards" they were fitted with something like a 92C/197F thermostat...and tuned to run lean...and choked down with pollution control...consequently, the slightest hold up in city traffic or running on a really hot day would see you boiling.

An 82C thermostat made the engine much happier (but I could have been arrested for abusing the environment!)

_________________
"Show me the Mini!"

More modern engines do run hotter. On my `97 Jeep Cherokee (4.0L AMC motor), 100C is in the middle of the normal range.
Mini owners worry too much. Unless your radiator cap doesn't hold its 13psi pressure, 100C in a Mini is nowhere near boiling.

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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.

For a while people were taking out the thermostat entirely... because they got too hot and presumably the idea was that it would increase the flow (but then in winter it didnt get hot at all!). The problem I think though was that the radiator is tiny on these things and whatever you did it would still get hot...! Now people tell me that the aluminium radiators are the fix for this.

Aluminium radiators have corrosion problems when old. And copper is a better heat conductor. Back in EA Falcon days, taxi operators used to replace the 1/2 blocked 2 core alloy rad with a 3 core copper one. Stopped my EA overheating when towing.

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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.

Just had a look at the BMC engineering drawing for the temp gauge - part AYA9168.

It says "52 degrees C at the Cold position and 120 degrees C at the Hot position".

_________________
ex-NSW Police 1970 MK II Cooper S
VMCI #43

So the middle is about 85!

Yes, I wondered about corrosion. Maybe use a lot of antifreeze?

Winabbey,

52 C at the cold position? Does that mean the lowest temp the gauge will indicate is 52 C I wonder?

_________________
67 Deluxe
Dry suspension
1293cc, 11:1 comp, RE 282 camshaft, 45 Weber, extractors etc
4 synchro close ratio gbox
Cooper S brakes, no booster
Stealth box, as Doc says "goes harder and idles!"
RH tank cos I needed it crossing the Nullarbor etc..

I don't know, but assume the needle is at rest at Cold and won't move until the temp goes beyond 52 C.

_________________
ex-NSW Police 1970 MK II Cooper S
VMCI #43