[72LS1Vette]

I would toss that manifold and put on a new one. The corrosion is caused by the reaction of dissimilar metals - iron heads and aluminum manifold. You can buy radiator caps that have a "sacrificial anode" attached that will cut down the corrosive effects of the iron/aluminum interaction. The anode will get eaten away rather than the intake manifold.

:cheers:

Rick B.