interesting link
http://www.guyons.com/racing_tips6.html
21 Reasons why your engine may run Hot. More Racing Tips
A lean air/Fuel Ratio (Also check fuel pump and Filter)
Too much timing/retarded timin/advanced curve malfunction
Clogged Radiator/Collapsed Hose (restricted water flow)
Clogged Engine (restricted water flow)
Stuck Thermostat / Incorect Thermostat
Bad Water Pump
Incorrect Water Pump Speed (too slow/too fast)
Radiator Too Thick
Wrong Pressure Cap
No Shroud Around Fan. Improper Fan Position Within Shroud.
Bad Fan Design - Stock Factory Type Usually Works Best.
High Volume or High Pressure Oil Pump
Electric Fan (Pullers/Pushers) Blocking Air Flow
Too Much Antifreeze
Wrong Type Antifreeze
Flow Test: Begin with cool engine. Remove radiator cap. Start engine. Bring engine up to operating temperature so that the thermostat opens. Increase engine speed to 2000 rpm. If water gushes out of radiator there is a flow restrictionin the system. This must be corrected for proper cooling.
Wrong Spark Plugs (ie. Heat Range)
Wrong Gasoline Type (Try 89 or 92 Octane)
Clogged Catalytic Converter.
Clogged Injector System.
Exhaust getting into the water due to a cracked head or blown head gasket. Have your local radiator shop test your system for carbon dioxide.
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1967 Firebird 400 conv T400 3.08, 1989 Formula 350 700r4 3.27