Originally posted by 72 chevy 4x4:
My truck has a 454 and it gets hot wether I'm on the hiway or in town. I've put a new thermostat in ,i have to 10 inch electric fans pulling air and flushed the 4 core radiator. I dont think i have a head gasket problem, that would be very clear. Water pump maybe?
I also vote for servicing the radiator.
Other contributing factors could be:
No shroud on the fans can cause overheating in stop and go traffic.
At highway speeds the most common cause of overheating with modified big blocks (even a RV cam will do it) other than a faulty radiator is the water pump/intake manifold bypass not leaving coolant in the radiator long enough to be cooled. I block it off and use thermostats with two 3/16" drilled holes for pressure release.
Last but not least are quality of pressure caps and thermostats. It's not at all uncommon to get defective parts in either one.