I got a problem of overheating on the highway, my thermostats 180 and its all good schooling cats on the streets, but when I hit the highway itll slowly climb untill i get off the highway.

Carb'd 355, no a-c, single fan radiator set up.

Any suggestions guys?

 

hmmm, sounds like the same problem I had with my camaro and I asked a question some what alike yours.

check under the front of your car, and under your raditator (sorry, probly miss spelled that) there should be a long black board under your car, (I guess I should just call it a Air Dam) GM put those on camaros cause they werent gettin enough air through the grill so they put those on under the car and pushes the air into your raditator.

it should look like the black board on this pic, if your car is missing that, then im sure that's the problem.

 

Ya I know what your talking about and its missing because the guys I bought it from got in an accident and didnt take it to a shop, he thought he would do it himself and now my rides missing a whole bunch of components, I will try to find one if you think thatll solve it.

 

Alright, I got mine at Hawk's third gen, it was sorta pricy there tho.. was like $80 for a plastic board

when I first got my car it would only over heat when im going on the highway but not in town or during idel, it was getting fustrating cause we put in two new thermastats, almost a new raditator, and new hoses and once some one on here told me about the air dam, got it, bolt it on and solved it.
let me know if that solves it.

 

That's what your problem is. These cars (especially the firebirds because they have no grill) are bottom feeders for cooling. Without that dam, almost no air gets up there at highway speeds.