I'm installing a 24" alum radiator w/ twin 12" electric fans in my '70 stang w/ a modified 289. I'm trying to figure out the best temp switch to install. I notice that Painless and others seem to use a 185 on and 170 off switch but a guy in our local club who was a Ford engineer says to use a switch that is on at 215 and off at 200. I've also been told that I would get better performance w/ engine temps in the 190s. I believe I have a 195 thermostat in the car now. I want to keep the engine cool so the higher temps make me a bit nervous but also want it run at optimum temps. Can anyone suggest the best switch range and explain why? Thanks again guys!!