Does the engine get hot right away or does it gradually get too hot? If the temperature steadily goes up to a certain spot and stays there, I would say your guage is inaccurate or something is regulating the temperature (like a bad thermostsat). If it slowly gets hot I would say it's a flow problem, like a partially plugged radiator. Possibly you could also be running too lean or have a headgasket out. I run a 350 in my truck with a radiator that would support a V-8 and it never gets up past half way on the guage, regardless of how hard it's pulling or how warm it is outside.
Scott
