LT1-LT4 Modifications - 93 LT1 Z28 overheating?

I have a 93 LT1 Z28. It has new water pump, hypertech 160* therm., both fans are on a toggle, full radi., shroud is in place. Most threads I find have been saying overheating while going slow or at a stop. Well mine is odd b/c it overheats bout 3k RPMs or while cruising with the AC on. Any help would be greatly appreciated. Thanks in advance. Robert

Did you bleed the system after all those installs? If not run the car at idle with the cap off of the radiator until the car has completely warmed up enough for the thermostat to open up (watch your temp gauge to the point it stops heating up and actually stays there or cools a bit). With the cap off it will allow bubbles (air pockets) to rise up and bleed out the resoirvoir. If not properly bled the air pockets can cause big problems.

Yeah we bled the system at the hoses. As soon the screws were opened we got a steady stream of coolant.

Yeah we bled the system at the hoses. As soon the screws were opened we got a steady stream of coolant.

did you wait for the thermostat to open? and what kind of waterpump? stock or electric?

+1 You have to make sure the thermostat has completely opened...

How old is that rad? When I replaced my rad, my cooling efficiency increased 10x.

I'd check the system for air pockets, but if that's a dead-end, consider the rad.

Stock water pump, can't remember weather the threm. was open are not, the rad. i think is the same age as the car.