I rebuilt a sbc 350 in my new to me pick up last fall. Rough weather hit a few days after the install and I had to wait for spring to finish all the little odds and ends.......I have found that the coolant is leaking at the hose spigot above the thermostat and the temp gauge is freakin out around 255-260F if it is accurate. My theory is that maybe the thermostat is no opening and the coolant is building pressure and finding its way out....Other than this it seems to be ok, knock sensors and all. Anyone have any input?