I was able to run more timing on less octane in the summer with a 79c Tstat in my M103. The downside was that I had to tape over 1/3 of the radiator in order to get adaquite heat below 45f ambiant. Small price to pay when you can handle summer temps in excess of 100f without a clutch fan while the temp gauge never went over 95c.

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CENSORED due to not family friendly words