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    Exhaust manifold port corroded (Merc 470)

    Not real familiar with that engine, but I'd shy away from trying to JB weld it (or similar). In general, the exhaust system tends to be quite hot, so the stresses don't take well to added material. You might check and see if you have room to have the manifold "decked". Think how a machine shop...
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    84' 3.0 Block & 91' HO Head Tuning?

    Update! Found Solution! After two hurricanes, a road trip, and a bunch of time in the office, I got back to the boat. Noticed it wasn't getting gasoline to the carb. Replaced the 34 year old fuel pump, and cleaned the carb all the way through, the engine ran like a top today. 3 hours on the...
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    84' 3.0 Block & 91' HO Head Tuning?

    Good evening all, Recently swapped heads on the old 1984 MCM 140 3.0 in the Chris Craft. Couldn't find the old style large port head, so had to go with the 1991+ high output head. Still using old manifold and carb, despite non perfect port alignment. Engine starts and runs well, but backfires...
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    1984 MCM 3.0 New Head

    Good afternoon all, Have a 1984 MCM 140 3.0 Liter that developed a pinhole leak in the number 4 exhaust port on the head. Can't find a new "big port" head, so bought a "high flow" head for 1991 and newer 3 liters, and the adapter to mate up the old manifold. The adapter is 5/8 inches wide...
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