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Engine bay expansion

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  • Engine bay expansion

    Does anyone have info on exactly where, how wide, the stringers are located in the 20's? I assume they must run from bow to stern along the engine bay and fore and aft compartments? Just outward of the drain channels?

    What I'm getting at is, can I expand the engine bay by 2- or 3 inches on either side without compromising the integrity of the stringers? I need to fit a Crusader 350 and it's a heck of a tight fit.
    It's mostly the exhaust manifolds that are the issue, they are much wider than PCM center rise manis. The mounts are the same, I installed the ford to chevy kit, so same footprint there.

    This drawing is not 100% accurate, but if I cut out the deck drain channels then go straight down to just above the engine beds, am I looking at disaster? Or, I could cut as a taper from the deck 3" out and bring it down to 0" at the engine bed.
    Click image for larger version

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    1986 20' Openfish PCM 302 RWC
    Marblehead, MA

  • #2
    If you cut out the stringer, what will hold your deck up?
    1988 26' cuddy
    1975 20' open
    16' Sandpiper
    14' Certified Fiberglass

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    • #3
      I'm not a naval architect but I play on in my back yard. My guess is if you reduce strength of those stringers, the last thing you'll need to worry about is your deck. My guess is the longitudinal structural strength will be weakened and the boat would be prone to racking and twisting under certain conditions.
      Hopefully someone will come on and say I'm dead wrong, therefore allowing you to do as you want.
      Please keep us posted.

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      • #4
        Actually in that area the engine bed would support the hull. Don't like the idea of cutting the stringer.
        1988 26' cuddy
        1975 20' open
        16' Sandpiper
        14' Certified Fiberglass

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        • #5
          I would swap the manifolds before cutting the boat. I thought the 20's were sold with 350's or 351W?
          Steve
          1998 260 Mackinaw Sea Maxx 5.7 HO TBI 12' Klamath w/ 20hp Tohatsu EFI

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          • #6
            I wasn't intending on cutting the stringer, mostly just "grazing it" or coming right up close. However, I found the solution after doing some careful measuring. I trimmed the inside gutter wall down about 1.5", it will give the manifolds ample clearance, enough so I can get at the plugs too, which was a major concern as well. Also, leaving enough of the gutter wall so it will still function as a gutter.

            Thanks for the input gentlemen, I'm glad I waited and thought about this a bit longer.
            1986 20' Openfish PCM 302 RWC
            Marblehead, MA

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            • #7
              I have a Mercruiser Chevy 350 in my 20ft Cuddy. Biggest problem I had was height.Top of engine box hit top of exhaust risers. Plus my alternator is on the lower port side forward.Not enough room to swing it out so that was my biggest modification. I used Chevy mounts and had to raise the mounts about 1-1/2" off the beds.
              '78 20ft Cuddy
              Mercruiser 350 FWC preVortec w/Carb

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              • #8
                Flatrock, I have done the same thing. Cut the gutter.
                1988 26' cuddy
                1975 20' open
                16' Sandpiper
                14' Certified Fiberglass

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