I know to help you need all the info, so...
1968 motor rebuilt and installed in a 1968 firebird convertible. The cam is a street/strip, idles fine, edelbrock 650 carb, and timed to about 13 degrees. I have a new 195 thermostat, water pump, radiator, and clutch for the fan. There is no fan shroud yet, but I've had a '68 without one before and it colled off just fine. Also, without air, it was not always installed. I have a coolant cap thats rated at 15 lbs.The darn thing gets real hot (according to the rally guage) and when I hit the hiway it goes to the max on the guage which I believe is 250? I put on an antifreeze bottle and hose to catch the overflow. It will overflow if I don't throw in the cluch and idle it as I'm doing 30+ mph to cool it down.
The water pump has the metal inserts in, and there's only one way to install them, but as I looked at the pump fins, they seem to rotate backwards from what I thought it should, but the new pump is the same as the old one. Maybe thats just the way it is.
Any ideas? Thanks