helllp with cooling issue

what i am trying to say is in my 72 duster with a mild 318 bored 30 over with a 340 cam the new radiator from advance with a reprodution shroud did the same thing so went with a new on from wizard cooling. it was alot of money but worth it. if you can find a factory three row it should also do the job. thats my opinion. i tryed every thing when i had the advance radiator from watter wetter to adjusting timing and carb.by the time i bought the radiator and shroud i could got a new aluminum fro champion which alot of guys run with success.