I agree with Steve (though I run a 180deg thermo year-round).
There are a couple other advantages to running a hotter thermo (180 or 190deg):
- at cooler temps, you have to run quite a bit richer for the car to run
properly
(lower mileage, more raw gas in the cylinders=more bore wear)
- with a 160deg thermo, your range of operating temps is much higher (possibly,
160-212 deg or higher). Your carbs can't automatically adjust mixture much
(SU carbs are, allegedly, somewhat altitude compensating), so if you tune
them
to run properly at 160, they'll be way too rich at 190 or higher (watch the
soot
build up on your exhaust tips on a hot day--same as running at a higher
altitude.
As an aside, this is known as "density altitude" and must be thoroughly
appreciated
by pilots. A sea level runway could have density altitude of 3-4,000 feet
MSL on a
hot day--bad news if your plane is overloaded or underpowered).
- generally, 180-190 degree coolant temp is optimal (most newer, injected cars
will run hotter/leaner than that). If your engine doesn't get warm enough,
you
won't be boiling off the water that condenses in your oil (this is analogous
to the start/stop, short trip "city driving" that new-car manufacturers call
"extreme
duty"--which requires more frequent oil changes).
I don't have an oil temp gauge, but I suspect running at 180deg coolant temp
equates to (at least) 212deg oil temp ... can anybody with an oil temp gauge
shed some light on this?
Don't know where the "winter/summer" thermostat stuff came from, but it's close
to urban legend in my book.
bs
***************************************************************
Bob Spidell San ose, CA bspidell@comcast.net
'67 Austin-Healey 3000 '56 Austin-Healey 100M
***************************************************************
I'm not sure why a lower-degree thermostat is considered appropriate for hot
weather. All it will do is open fully at a lower temperature. Once it's open
fully, it isn't going to do anything more for the cooling, and it certainly
won't keep the temperature from going above 160. A 190-degree thermostat will
be just as fully open at 190-degrees coolant temperature as a 160-degree 'stat
at 190 degrees. For a cooling system in good shape, a 190-degree thermostat
should be good for year round.
What the lower temp thermostat can do is make the engine run too cool in the
winter. Again, when it's fully open at 160 degrees, it is out of ability to
control the engine temp. A 190 can stay partially closed to restrict coolant
flow and bring the temp up closer to normal operating temperature (190).
It doesn't do any harm to run a 160 (or no) thermostat in the summer, but in a
cooling system that's in good shape, you'll probably have to change to a
higher temp thermostat in cooler weather or watch the temp gauge stay around
160 - 170 degrees.
Steve Byers
HBJ8L/36666
BJ8 Registry
Havelock, NC USA
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