On Sun, 12 Jul 1998 14:40:34 Barney Gaylord <barneymg@ntsource.com>
writes:
SNIP SNIP
>In your case it probably doesn't make much difference. The thermostat
>controls the minimum operating temperature of the system, not the
>maximum.
>IMHO, 165dF is too cool for an MG engine. At that temperature it it
>may
>not vaproize the fuel in the carbs well enough, results in carbon
>buildup,
>raw fuel in the exhaust, occasional misfire, and possibly a little
>loss of
>power. If your temperature is running on the high side, the low temp
>rating of the thermostat is irrelevant, because it would be wide open
>anyway.
Barney,
I'm gonna have to repectively disagree with you here.
Without getting into the numbers game, the why's and wherefor's etc.,
I'll give you the data on my car (1972 MGBGT). The car has a standard
cooling system, running about 50/50 water/antifreeze, and I try to keep
it in good working condition (ie. periodic flushing, maintenance etc.)
The summer temps here in SC run in the 90's with the ocaisional burst to
100. Winter temps are highs 40, lows near 20, on the average. They have
gone as low as 0 on the rare occaision.
With a 180 thermostat in my car year round this is what I have found. In
the summer the temp gauge hovers about 1/2 way between "N" and "H", or
somewhere around 200-210 degrees, if I am interprolating the guage
correctly. On a long pull say up a mountain grade, the guage would start
climbing.
In the winter, the guage would never reach the "N" and stayed a bit
over midway between "C" and "N". On one club trip on a cold day, I was
forced to block the radiator about halfway up to get the temp to any
where near a normal temperature.
When the problem with the 180d became apparent, my first thought was a
bad 'stat. It was duly changed with no result.
Now I run a 165d in the summer. The same guage will indicate about one
needle width below "N", until I hit that long grade, when it will rise to
the right edge of the "N", but no further.
In the winter, I switch to a 195d thermostat. In town or on the highway,
the needle seems to be stuck on the right side of the "N".
The only difference seems to be that the 195 takes less time, even in
the winter, to reach it's norm, compared to the 165 in the winter.
What It all means, I'll leave that to others. All I know is that since I
started switching the 'stats' in the spring in fall, cooling problems
have been few and far between.
Now, I'm gonna stick my neck out and theorize. I think that the quicker
opening 165 allows the radiator to begin cooling engine coolant sooner,
and because it is wide open sooner, allows full flow at temps below 180.
The 190d "winter" 'stat, by delaying opening till later, allows the
engine to reach normal temperature sooner, but the much cooler ambient
air temp will transfer much more heat fromt he radiator, the rise into
the "critical zone' is avoided.
Nomex skivvies are in place for any potiental flames.
Rick Morrison
72 MGBGT
74 Midget
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