I got an electric fan today and I need to put in a fan switch but not sure on what the best temp range is. I was thinking about having the fan come on about 210 degrees. Is that too low or too high? I have a 347 with aluminum heads and intake. Also the fan is a flex-a-lite lowboy trimline capable of 2500 CFM.

 

I say 197-205

 

I used to know a retired Ford engineer who worked on these engines. They were designed for optimum performance using a 190°F thermostat.

 

my 347 stays about 190-200