I've got a rebuilt 350 that was just put in to my '88 bird. I have a new radiator w/ it. I'm currently using the electric fan from the V6 that was in prior to the V8. It runs hot, all the way up to 245 degrees, then at idle begins to cool to 215-225. The thermostat is marked for 160 (the thermo works and is allowing flow). Could it be that the fan i have from the V6 is crap? I'm planning on ordering a 16" Perma-cool high perform. 2,950cfm electric fan from Summit. This should fix the prob right?

 

If you car runs hot at speed and cools at idle, it is most likely a problem of airflow through the radiator at speed. My guess is that you are missing your flexible lower spoiler, they often get torn off over time. Firebirds have no "grille", so without the spoiler extensions under the chin of the car, the air goes under the car instead of up into the radiator. Make sure this is on there, and tilts forward instead of being bent back, or the car will overheat at speeds above about 50-60 (mine did!).

Good Luck
Troy
So Cal

 

As TA said, additionally your timing may be off as well.

 

Well, i got a hold of one of those temperature gauges that will give you the temperature of anything by using a laser. I've pointed it at just about every point on my engine, focusing on the port on top of the intake manifold where the coolant exits. I'm reading 200-215 from the laser, when my gauge in the dash is reading about 240-245. So, to conclude, my gauge is definitely off. Can I get by with running 200-215? Or do I need to get it to run cooler. I'm gonna recheck my timing again as well, I don't have the tool right now, I have to go somewhere else later.

 

You are not reading coolant temp that way, you are reading the temp of the surface of the metal. This will be significantly different.

Does the car act hot, boil the coolant and gurgle when you shut it off, do you feel a wave of heat when you open the hood? Does it idle a little funky and not have a lot of low end power? These all indicate it is really hot.

I would swap to a cooler thermostat to start with, maybe 160 degrees, and see what happens. It should open sooner and not let the car heat up.

I hope this helps

Troy
So Cal