I guess my dumb question would be do you have a fan shroud or just blades setting behind the radiator.

If no shroud the air is not pulled through the radiator in total but pulled in from sides behind the radiator.

When I put a 350 into a land cruiser and ran no shroud I ran hot, especially when setting still.
But once I built the shroud my temps drop down to thermostat level.

Baking in the nice desert sun, breathing life back into a 48 3800 5 window.