My 69 350 slowly overheats as I drive it. It has an aftermarket aluminum radiator that was in the car when I bought it. I have since added a high performance electric fan with shroud. It still slowly gets hotter and hotter as I drive until it gets to 210 to 220. If I stop at a red light it get hotter much faster. Do I need a bigger radiator or can I try a smaller water pump pulley to speed up circulation? Or are there other considerations? thanks in advance

 

your radiator either does not allow enough flow (may be partially clogged) or your fans are not enough

Assuuming your radiator is in good shape and the fans put out enough....Check that you don't have to much timing