I have a late 70's(?) 350 Chevy OMC with Mercruiser outdrive. I removed the Merc (black) port side exhaust manifold to replace with a new one. The new mani comes with a gasket that allows water to flow from the mani to the elbow. The old mani has a gasket and what appears to be a thin sheet of Stainless that BLOCKS the holes for the water jacket so that it WON'T flow into the elbow. There is one small hole at one of the water ports. Do I need to block the new or let it flow, let it flow, let it flow???
Thanky!
Thanky!