I recall John Twist reporting here that 190 degrees F. was the optimum
temperature for the B engine. If you run at too cool an engine temp, the oil
never gets warm enough to evaporate condensed moisture and fuel seepage, so you
wind up with "mayonnaise" in your rocker cover, and elsewhere. Judging by my
mechanical temp gauge, even a 190 doesn't keep the engine at 190 except at high
speeds in a very warm climate, or in stop and go traffic with insufficient air
speed through the radiator. I keep a 190 degree thermostat in year 'round, and
would advise the same unless your engine overheats with that rating. I know
almost nothing about thermodynamics (other than how to spell it -- I was an
English major, not an engineer), but with a pressurized radiator, I'm sure our
engines aren't going to boil over until the temp goes well beyond the 212
degrees of an unpressurized container.
1967 MGB GT in sunny (today, at least) Seattle, WA
> Over the weekend . . . I assumed my thermostat was gone and
> replaced it. I bought a 160 for summer. When I took the old one out, it
> was a 190. What would be the logic of having a 190 thermostat in
> Phoenix (where my car came from)?
> With the 160 in and the engine warm, the temperature gauge registers
> about one-third of the way between cold and normal. Is that about right
> for a 160? With the 190 in, when it was warm, it would sit dead on
> Is there a problem running the engine at this cooler temperature? Should
> I put in a hotter thermostat? Any advice would be greatly appreciated. I
> live in Montana if that adds useful information.