"I have an 88 BAJA with a 7.4
"I have an 88 BAJA with a 7.4 gen IV mercruiser, bravo 1 with thru hull exhaust and square port heads. On both heads there is a rust hole about the size of a dime in the exhaust port. If you lay the heads on a table with the ports facing you (manifold side) its the 3rd port to the right. SAME EXACT SPOT, SAME EXACT HOLE!! If you look into the port it is right where it turns downward. The ports have extensive surface rust damage on the part that separates the exhaust gas and the water. The front and rear ports are PERFECT and the 2nd ports to the right have a little corrosion. My wild guess is that it is some kind of galvanic corrosion. Does anyone know where to get a set of square port gen IV heads?"
"I have an 88 BAJA with a 7.4 gen IV mercruiser, bravo 1 with thru hull exhaust and square port heads. On both heads there is a rust hole about the size of a dime in the exhaust port. If you lay the heads on a table with the ports facing you (manifold side) its the 3rd port to the right. SAME EXACT SPOT, SAME EXACT HOLE!! If you look into the port it is right where it turns downward. The ports have extensive surface rust damage on the part that separates the exhaust gas and the water. The front and rear ports are PERFECT and the 2nd ports to the right have a little corrosion. My wild guess is that it is some kind of galvanic corrosion. Does anyone know where to get a set of square port gen IV heads?"