Help with radiator

Another idea along the airflow theme…does the fan sit IN the shroud and not BACK from it? At low rpm that could limit the airflow. If it does, a spacer should be able to get it closer…I don't know how close is too close…just an idea. The high flow water pump crossed my mind as not optimized for low rpm like idle…but I'm no engineer…could also have a problem like Bksgonzo mentioned above. I'm interested in finding out what solves your problem. My 340 always ran hot…I took the thermostat out of it…still would creep up to limits at idle. I'd like it to run cooler. Keep us posted on what you find out! Mark