Originally Posted by 496CHEVY3100
Normaly a hot idle is an air flow problem not a water flow problem in my experience ,are you running a fan shroud and a two speed fan ,and is thermostat housing lower than radiator car to prevent air pockets,,,i had to make a shroud for my radiator fan it would overheat at idle 220 and still going had to shut it down and leave fan running to cool it down ,after I made the fan shroud it rons about 190 idle as long as I need to, this might not be your problem but it sounds like it.
It runs hot at speed, or idle, but hotter at idle. I'm running an aluminum triple pass 19"x24" radiator, with two 1" rows. Also running a electric puller fan, and it's single speed 2800 cfm Spal. The fan comes on at 180 degrees, and it pretty much runs all the time with the temps the engine runs at. I am going to try an auxillary radiator to see if it's capacity, or air flow, and run cooling fans on it also.