I have a 65 riviera that runs great but over heats. I have change the thermostat, radiator, water pump, double checked the timing, and switched to a electric fan. The car won't heat up at idle but as soon as I drive it, it gets hot. I was wondering if anyone else has ran into this problem. I'm leaning towards it being a head gasket but it's not blowing steam out the pipes. I'm going to try a block test sometime this week to see if it picks anything up.. Thanks Casey