OK, my 350 TPI has just been currently rebuilt, bored .30 over, new crank, huge cam, ect..... the whole works, and Ive been experiencing a bad problem with my car running WAY to warm.

My driver side fan runs ALL the time, wired that way when I got the car.

My question is this, If I buy ONLY the Fan Switch in this link,

1984-91 Low Temperature Electric Cooling Fan Switch - Corvette Parts & Accessories by Mid America Motorworks, 800-500-1500

Will this switch make my passenger side fan turn on at 200 and off at 185 like it says it will?

 

The drivers side fan is controlled by the ECM from the OEM, sounds like its been hard wired. Replacing the fan switch (the part you linked) should make the pass side fan turn on earlier, highly recommended. I would match the fan switch to the thermostat in terms of the temperatures they activate. But some other questions ..

Do both fans work?
Was the thermostat replaced?
What temp thermostat is it?
Is the coolant dirty or discolored?
What kind of coolant fluid are you using?

And probably most important ... when does the problem happen? (while at a stop? while moving above 35 mph? all of the above?)

 

Well, to start off,

Both fans DO work, the one runs full time and the other comes on when AC is on, along with when the temp is reached to kick it on automatically.

The thermostat WAS replaced.

The Thermostat is 180*

The coolant is a green color.

The coolant fluid is a 50/50 Mix of antifreeze/water.
I dont remember what brand though.

Also, when I got home from driving one night, the temp was reading 235+ , I popped the hood to check if my overflow was bubbling out, well, it wasnt, it was right at the line of "FULL HOT"

The car will warm up as normal, hit the 190 mark, stay there for a while, then steadily climb to 235+ and STAY there.

The car will heat up to 235+ EVERYTIME the car is driven for say half an hour, no matter if im in stop and go traffic, or going 60 down the highway (even though it does run a tiny bit cooler on the open road, but even that's barely noticable.

 

I was thinking the problem was the fan switch all the way up to the point where you said it happens while driving too. When you're moving highway speeds there is enough airflow to cool the radiator down, dosnt matter what the fans are doing at that point. This leads me to believe your problem involves the thermostat somehow. The coolant would be getting cooled but dosn't seem like its making its way to the engine, so the thermostat is stuck or its opperating temperature is different than what you think (maybe its a stock replacement?). Either that or the radiator isn't working properly and the coolant is not being cooled regardless of how much airflow you generate. An easy way to test this would be to remove the thermostat and drive the car on the freeway again and see if it acts differently. If the car stays cooler at freeway speeds then you know it had something to do with the thermostat. If the car still heats up with no thermostat then I would be looking at the radiator. After doing this test I would buy a new 180 degree thermostat since they are so cheap. I would also drill a 1/8th hole into the fin on one side before installing. But thats just how I do it.

 

I'de say your problem has more to do with your air dam and possibly debris stuck in the ac condensor or even the radiator. Try taking it to a car wash and really getting the power washer down in between the radiator and the condensor if you have one plus make sure your air dam is in good shape. You may also want to try going down to a 185 T stat with 2 small holes drilled in the flange to allow some coolant flow before the thermostat opens (basically what CrazyHawaiian recommended). PS it's a really bad idea to run a car without a T stat, you reduce the pressure in your cooling system and this can cause hot spots to form in your heads and your coolant to boil over at a lower temprature, if you want to try running it with no Tstat you really need a restrictor plate or a gutted thermostat top.

 

Well, last night, my car warmed up right near 250, I got home ASAP and made sure the fans were spinning......

The Passenger side fan WASNT Spinning!!

I am going to buy another T-Stat and drill two 1/8 inch holes in it.

Ill report back with results