I installed the Dual electric fan setup from a Ford Windstar. I ended up buying a Painless Wiring fan controller that is suppose to kick on at 200 degrees and off at 185. I put the sensor for the fan controller in the intake water jacket just to the right of the thermostat (180 degree). My temp gauge under the dash has it's sensor in the head on the drivers side.

So, I start the car, 1972 Chevelle with 350, and according to the temp gauge under the dash the fans kick on at 215 and off at 195. I called Painless and they said the temp gauge under the dash could be off a little plus the temperature in the head will be higher than in the intake. I did shoot the intake with a infared sensor and it reads accurately at about 200.

So ... do I trust that and let it ride? I feel like I want to order the 185/170 sensor so the fan kicks on earlier.

As a side note the fan controller is only hooked up to the larger of the 2 fans on the passsenger side where the upgraded alternaor is as well to help cool it. It will drop the temp about 20 degrees in about 2 minutes. I have the 2nd smaller fan on a toggle switch and relay if I ever need it but I don't think I ever will!?!

Head temp will usually run 10 to 20 degrees more than intake temp. Sounds like you need the other sensor since you're running a 180 thermostat the intake should be at 180. Your fans aren't kicking on until it reaches 200.

Well, I checked it again with the gun on the intake where the sensor for the fan is mounted and sure enough, it kicks on at 200 and off at 185 like it is suppose to. So ... if the head is 15 degrees hotter and getting up to 215 is that really a problem? What would you do with your Chevelle???

Well let me ask this. Why are you running a 180* thermostat? Do you want the engine to run at 180 or do you want 200? The rad can't do it alone, it needs the fan, so why run a 180 thermostat if the intake temp is going to 200 until the fan turns on? I suggest the other sensor, 215 is not bad but if you could pull it down to around 200 that would be better.

Therein lies the question ... do I want to focus on the thermostat/intake or the head while designing how/where I want to cool my engine. This is a daily driven, camper pullin' 13 second race car that my 2 year old grandson absolutely loves to ride in!

I took her out this weekend for a bit and if the car is moving it keeps itself cool around 190 degrees. This is true at 30mph or 60mph. Granted it was only about 60 degrees outside but I am still impressed and pleasantly surprised. Plus, my fan never even needed to kick in!