alternator on a Mercury 4-bolt manifold

[Ross F-1]

I have the same manifold on an 8BA (I assume that's what you have?) with a 10SI, no problems. Are you running the fat belts or the two narrow belts?

3/4" is a lot, could you have the alternator on the wrong side of the slingshot mount? I know there is a difference in the slingshot mounts used on Trucks with the 8BA vs the Cars. I don't think it's quite that much difference tho.