[Michael C Henry]

Did you or are you using a thermostat with one or more small holes in the thremostat disk? Have you eliminated the original thermostat bypass hose.? I recamend keeping the thermostat bypass and a thermostat with one or two small holes. I had a brother-in-law that had a 84 F250 with a 460. It kept blowing all the coolant out ofv the coolant recovery tank. I found thet the short hose inbetween the intake manifold and coolant pump had an internal blister that closed off the bypass flow when hot. The blister was not visable from the outside but when that short piece of hose was just removed the inside was allmost closed off. So I reccamend keeping the original thermostat bypass system so coolant keeps circulating in the engine block.
The small holes are allready installed in some thermostats. they let the air circulate out of the coolant system and don't really affect the flow so the thermostat can better sence the coolant temperature and open and close . Another FE trick If you are using the original large diameter thermostat style it has a large body and a small valve to let coolant go to the radiater. Chrysler products have a direct relacement that is large thermostat to fit the pocket in the FE manifold and uses a large valve much like a GM thermostat, but the whole thing is larger to fit the pocket. I have alluminum heads and I don't like the temperatures getting too high. Also if you start getting above boiling temp and the coolant could boil and seperate into a gas like steam and steam doesn't remove heat from the cylinders or head as well as a liquid.
I also use thremal sensors that are in contact with the top of the radiator that transmit to an adjustable switchs and then to relays to turn on the fans. I have four sucker fans, the two at the top are wired together and the two lower fans are wired together. I also have a bypass switch on the dash to take manual control before things get out of range. Keeping the car moving is the biggest part about keeping temps where the thermostat is actually set.
Also my car has the widest radiatot that could fit up in the nose and has a lean back the top. I have to lower the radiator out the bottom