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  1. #1
    Piston? WHAT Piston?!? JGringo's Avatar
    Join Date
    May 2007
    Brookfield, WI/ Des Moine, Iowa/ Houghton, MI

    Sanding and polishing Exhaust Mani for 780?

    I have the ports all polished to a mirror finish on the cylinders but would polishing the manifold help as well? Getting all the way through? Right now its rough from carbon build up and the stock forge of the manifold is rough as well... Anyone think it would be worth it?

  2. #2
    Lake Mead Bum & BTLS Mark starflight's Avatar
    Join Date
    May 2007
    Boulder City, NV
    Last winter, my project was doing head work on my 4 cyl boat. I had hardened valve seats installed and a valve job done. The valves were not in bad shape. I ported & polished the exhaust ports on the head myself. I also polished as far into the exhaust mani as my dremel would go. I picked up 400 rpm by doing so. I had to get a prop w/ more pitch to keep the rpms in the range it should be. My other prop. is a spare now.
    I say, if you have the time, go for it. It cant hurt. You may have to adj. the fuel air mixture. I had to richen up the carbs on my boat.

  3. #3
    Join Date
    Jul 2007
    Cedar Rapids,Iowa
    It wouldn't hurt,the matching of the jug,gasket and exhaust is the most important.

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