Announcement

Collapse

ONE RULE

Consider this your neighborhood bar,corner soap box, fish house, marina, coffee shop or anywhere else you go to hang out with friends and talk anything you want. Only thing, personal attacks will not be tolerated. No name calling or belittling. Be civil at all times and have fun. If a topic offends you, don't read any further.
See more
See less

Side Project - 351 teardown and rebuild

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • Side Project - 351 teardown and rebuild

    Hope all is well to each of you in the boating world. I'm headed down to Long Neck tonight to spend two days with the boat and my wife (no kids!) out on Rehoboth Bay. Here's hoping the boat runs as expected.

    Anyway, I've got two FWC Mercruiser 351s sitting in storage. They need to be torn down to determine if they're even usable, and what all parts I might be able to avoid switching out. So, I thought maybe I'd work on them this summer. Before I do though, I've got a few questions.

    First, if I find out I can tear them down and rebuild them - or even make one out of two, can I get a 351 into a 20? I imagine it would just give me more torque at a lower RPM than the 302 IF it will fit at all. (If I have to raise the motor box a few inches that's no big deal - I'm more concerned with width.)

    Second, being Mercruiser conversions, are there any parts on there I should or shouldn't use? I'm running a RWC PCM 302 so that's pretty simple. I'm hoping to learn a bit by disassembling these, so whether I decide to use them or not I'll probably go ahead and take them apart.

    There isn't anything wrong with my current setup, but it sure would be nice to have a motor at least in progress in case something does go awry. I don't know - what else am I missing about rebuilding a marine engine?
    Chip
    Camden, Delaware

    1989 Shamrock 20 Cuddy Cabin (Rock Bottom)
    PCM 302, RWC

  • #2
    It fits, I have had a few 351s in my 20. That narrow 20 will run 40mph and handle ok.
    1988 26' cuddy
    1975 20' open
    31 Grand Slam
    16' Sandpiper
    14' Certified Fiberglass

    Comment


    • #3
      In all honesty I think it's easier and cheaper to go the Longblock route. Unless you want something custom or enjoy doing it yourself. If you want to add fresh water cooling or such there are resources to help you with that.

      I have done the longblock route myself. Just have to make sure all the peripherals will fit. My 20 ft Cuddy was modified with a "new" 350 Chevy Mercruiser. But the alternator hit the gutter so I had to get a shorter belt and trim the bracket. But with a little foresight you can
      '78 20ft Cuddy
      Mercruiser 350 FWC preVortec w/Carb

      Comment


      • #4
        Thanks fellas. Just for fun I think I’ll take them apart down to the block and see what I can learn. Wouldn’t mind using the bellhousings with the starter on top either! May take me all summer, but I think it would be good for me.
        Chip
        Camden, Delaware

        1989 Shamrock 20 Cuddy Cabin (Rock Bottom)
        PCM 302, RWC

        Comment


        • #5
          I'm doing the same thing as we speak. Let me know if you need any parts.
          1980 pilot house 351
          1988 260 predator 351

          Comment


          • #6
            Originally posted by My My Hey Hey View Post
            I'm doing the same thing as we speak. Let me know if you need any parts.
            Will do! I’m not real sure what I’ve gotten myself into! Lol
            Chip
            Camden, Delaware

            1989 Shamrock 20 Cuddy Cabin (Rock Bottom)
            PCM 302, RWC

            Comment


            • #7
              Chip, If you look at my avatar on SBOers site you will notice that my engine is a rebuilt 351 in a narrow body 20. It is fun but you can get a long block for about the same dollars. I did put a custom cam in to get more torque in the lower RPMs but be careful when doing that because some of that torque is achieved by what is called valve overlap. meaning the valves are open together which in turn causes a little vacuum in the exhaust. That can suck water back through the exhaust valves.
              Atlantic City, NJ
              1982 Cuddy, Rebuilt 351 .060 rings, Edelbrock carb

              Comment


              • #8
                That valve overlap caused Carolina Classic a lot of money for replacement, under warranty, of 454s.
                1988 26' cuddy
                1975 20' open
                31 Grand Slam
                16' Sandpiper
                14' Certified Fiberglass

                Comment

                Working...
                X