Put the thermostat back in. It is an intregal part of the cooling system and actually serves as a restrictor plate to slow the coolant down to allow better heat transfer from the motor to the coolant and then from the coolant to the radiator.

What vehicle is this 460 in? '69 Lincoln? They should have come stock with a 10-1 compression big block. When does it get warm, only in traffic or going down the road too? How are you hoses? Especially the lower radiator hose, make sure they are not collapsing. Do you have a coolant recovery system, do you see the water level going up and down in the reservoir?

Pat