What engine, rad, modifications, did it ever work correctly, heater hoses connected, bypass hose connected?
It's a /6 with the using the radiator it was born with I assume. I should have mentioned that last year around this time I bypassed the heater coil and looped the heater hose.
When you say the rad was dry, you mean coolant below the core, or if you open the petcock on the rad nothing would come out.
Yes, the coolant was below the core. Not sure if there would be anything draining if I opened the petcock.
Does your overflow have a vent? If not it would preasurize and could blow the overflow hose off.
The only vent I'm familiar with is the one on the neck which the overflow hose connects with.
how often since you flushed has the engine reached full operating temp?
I would say a couple dozen times.
Are you sure the thermostat is installed correctly?