440 overheating at idle

Something else I noticed from your pictures is the distance from the tip of the fan blades to the edge of the shroud. The tighter the clearance here the better a ducted type fan will work. And yours seems to have a lot of clearance.

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If I go with an electric fan, I plan to go back to Coldcase (I really like the radiator). They have. Fan / shroud combo for the radiator. The pic of the fan is deceiving, I was nervous it was too tight. The shroud is stock Mopar and the clearance at the top and bottom is only the width of my finger. I think moving the fan and sealing the shroud will do wonders