I have a 91 Z28 350TPI with dual fans. They both work but on hot days it runs hots past the 220 mark to near the red line on idle at stop signs.
My question is, at what temp does the primary fan come on and can I replace the fan switch to change it to where it comes on at a cooler temp, and where is it located on the motor? and do I need to change the thermostat to match? (whats the best brand thermostat)
Do the local parts store sell the cooler fan switch??

 

Not sure about the primary temp, but the second fan kicks in about 230 or so. At that point, the 1st fan hasn't been getting the job done. Check Summit for HyperTech or some brand like that, they sell cooler fan switches. I have an 89 Formula, my sensor is located on the passenger side of the block, just above the knock sensor. It has one wire coming from it, going to the fan. FYI, the coolant sensor on the driver side controls the guage, and the one on the front of the manifold sends info to the ECM.

There are 2 other solutions, and I have both b/c the 1st time my car reached 240 in the parking lot a couple June's ago, I got serious about saving my headgasket. One is a cooler thermo. I run a 170* (Delco), got that at oehq.com. There is a 160/165 and a 180. I live in Virginia, so I really didn't need a 160, and 180 was a bit less than I wanted. I think you can get those thermos at the local Advance Zone. The other thing I did was the manual fan switch. I still have the stock 230 sensor, so it is more of a fail safe than my only safety net. I like control, I am a Taurus. So when my bad boy even sniffs 200, I flip the switch and cool'er back down.

If your mad about cooling, get a Be Cool aluminum radiator along with any of the other things mentioned and you engine may send you an Xmas card this year

Hope this helps..
Eric