When I changed radiators on my '37, the lower inlet was in a different place so my fan wouldn't fit any more. I had to step down one inch in diameter to a 17" low profile Flex-o-lite fan. These are the sharp as razors, stainless steel jobs that don't pull much air. The 17" was really bad at idle so I changed out the water pump pulley to a much smaller one. This not only spins the fan faster but also moves more water at idle. On the road its probably robbing hp, but for now its working OK till I figure out how to get more fan space. It did solve my heating problem.
You haven't changed pulleys have you?
Harbor Freight sells the infra-red heat guns.
Joe
