Thanks everybody for your responses. I have desided not to put a larger size pulley on the water. As I said, I do have the 3 core aluminum radiator coming. I don't think there is a cracked head, block or blown head gasket. Timing might be an additional problem. The distributor is an HEI. Going to pull it and put it on a machine to make sure that it is getting enough advance at higher speeds. It's not a problem right now with the sub-zero temp we have had for the last week. But, summer is only 4 months away.
The radiator that in it is aluminum 2 core and is only about 5 years old. When I installed the a/c late last summer this problem started.
