the kellison/vern setup has a lot to be desired, do you have dual fans? no shroud?
take a look above the Rad. is there a gap there?
changing the dual fan set up will help. adding a shroud will help even more. blocking the gap above the rad. will make all of the air, coming through the grill, go through the rad core.
lincoln mark VIII or ford taurus fan assemblies work really well, or, you can do a custom, i did a custom flexlite with made up shroud..