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5.0 5.7 Vortec heads

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  • 5.0 5.7 Vortec heads

    I have a 1996 5.7l Vortec engine I pulled from my Suburban 1500 with a spun bearing. Will the heads from this truck motor fit on my 1993 Mercruiser 5.0L motor to try to increase HP.

    I also wanted to thank everyone for all the help at the begining of summer. My boat ran great after all your help. I'm still only getting 28 mph and want more power for next year. Thanks, Mike


  • #2
    Re: 5.0 5.7 Vortec heads

    They will probably fit, Im a Ford guy. But they are most likely exactly the same heads.

    If your only getting 28 MPH with a 5.0 you got other issues.
    2011 Triton 190 Escape SE 150 Mercury Pro XS

    I never learned much from winning, but always learn from failure.
    Semper Fi

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    • #3
      Re: 5.0 5.7 Vortec heads

      They will bolt right up to the block, but you need a new intake manifold to match the heads...
      sigpic

      1969 StarCraft Chieftain, 4.3 Mercruiser Alpha One Gen II

      Link To Restoration Page


      ----------------------------------------------------

      Its What I Don't Say You Should Be Worried About...

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      • #4
        Re: 5.0 5.7 Vortec heads

        Originally posted by bifflefan View Post
        If your only getting 28 MPH with a 5.0 you got other issues.
        His issue is that he has a big boat. 24' from what I saw in a previous post of his.
        1998 Wellcraft Eclipse 24 Cuddy
        Volvo Penta Duo-Prop 7.4L "LK"

        2006 Sun Tracker Party Barge 21
        Mercury 90 4-Stroke FI
        "Common sense is not very common"
        "Failing to prepare is preparing to fail." -- John Wooden

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        • #5
          Re: 5.0 5.7 Vortec heads

          Will the heads from this truck motor fit on my 1993 Mercruiser 5.0L motor to try to increase HP.
          Nope,... The valves are bigger/wider on a 350, because the cylinder bore is larger...
          The valves will/ might hit the edges of the cylinders...
          If they don't hit, they'll be shrouded, 'n not breathe properly....

          Basically, 350 heads won't go on a 305, 'n 305 heads don't work on a 350...
          Any Grease is Better,..... Than No Grease at All.......

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          • #6
            Re: 5.0 5.7 Vortec heads

            Along with what Bondo said, 305 heads are usually 58cc where 5.7L vortecs are 64cc. That would lower the compression and reduce power as well.

            With a big boat, just rebuild that truck 5.7L and put it in with most of the marine parts from the 305.

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            • #7
              Re: 5.0 5.7 Vortec heads

              So it sounds like the head swap won't work. My next step was to rebuild the 5.7 truck motor like Imported_John_S mentioned. Will I need to change the Cam? Also can someone recomend a performance Marine Intake for it?

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              • #8
                Re: 5.0 5.7 Vortec heads

                The cam from the truck engine would work in the boat application as well. But wouldn't you want to replace the camshaft/lifters due to age, anyway?

                Comment



                • #9
                  Re: 5.0 5.7 Vortec heads

                  Like I said the 350 Vortecs will bolt right on your 305 block. Been there, done that on my old Camaro.

                  The problem was keeping the compression ratio close to stock.

                  The stock compression is 9.3:1 using (305-5.0) 58cc heads.

                  If you go up to(350-5.7) 64cc heads (Vortecs) then use Felpro embossed shim gaskets then you'll stay at 9.26:1 compression ratio. You just have to make sure the deck on the block is true, as well as the heads.

                  Having said that, you will probably not want to run those type of head gaskets on a raw water cooled engine if you run in salt water. If you choose to use stock thickness head gaskets for marine use you will lower your compression ratio enough that the extra HP gain from the heads will become negligible. But they can and do bolt up...
                  sigpic

                  1969 StarCraft Chieftain, 4.3 Mercruiser Alpha One Gen II

                  Link To Restoration Page


                  ----------------------------------------------------

                  Its What I Don't Say You Should Be Worried About...

                  Comment



                  • #10
                    Re: 5.0 5.7 Vortec heads

                    I'm for rebuilding the 5.7 and droppin her in...
                    You meet the nicest people at the American Legion.
                    "maintenance is always cheaper than neglect"
                    "certain parts are USCG approved for a REASON"
                    "just because it's in the factory service manual, doesn't mean it's correct"

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                    • #11
                      Re: 5.0 5.7 Vortec heads

                      I believe they are the same. The part numbers for the heads between a 5.7 and 5.0 are the same in the Volvo and Mercruiser parts lists at least. Both 5.0 and 5.7 each have 2 part numbers listed and they are identical for each motor.
                      1998 Wellcraft Eclipse 24 Cuddy
                      Volvo Penta Duo-Prop 7.4L "LK"

                      2006 Sun Tracker Party Barge 21
                      Mercury 90 4-Stroke FI
                      "Common sense is not very common"
                      "Failing to prepare is preparing to fail." -- John Wooden

                      Comment



                      • #12
                        Re: 5.0 5.7 Vortec heads

                        Originally posted by bruceb58 View Post
                        I believe they are the same. The part numbers for the heads between a 5.7 and 5.0 are the same in the Volvo and Mercruiser parts lists at least. Both 5.0 and 5.7 each have 2 part numbers listed and they are identical for each motor.
                        The standard 305 heads were 58cc and had smaller valves. I believe they had recessed/dished pistons. I am wondering if the 305 vortecs, if they do use 350 heads, are they running a flat-top piston to match with the larger chamber?

                        I still vote for the rebuild 350, though.

                        Comment



                        • #13
                          Re: 5.0 5.7 Vortec heads

                          The Votrec heads flow better and they will fit on the 305 but you will need to use a new intake manifold. I put the Vortec heads on a small block that was stroked, has 9.1 compression and then went with a marine cam to get the power I wanted to move a big heavy boat. Best thing I ever did, gets the boat on plane with only 1/2 throttle and don't have to use the trim tabs and it seems like a completely different boat. Went with more prop and gained a bit more speed as well with out the hassle of converting to a big block, it idles smooth and is good on fuel. I vote for rebuilding the 350, using the vortec heads, good cam and quality parts and you won't be sorry.

                          Comment



                          • #14
                            Re: 5.0 5.7 Vortec heads

                            As has been said before " nothing replaces cubic inches". If you have big boat syndrome you need the bigger 5.7 anyway so why keep patching the 5.0?
                            2008 Tahoe Q7i 5.0L MPI Mercruiser/Alpha One Gen II Drive
                            14.25 x 17 Michigan "Apollo" 3 blade Stainless (From iboats store)

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                            • #15
                              Re: 5.0 5.7 Vortec heads

                              Originally posted by spdracr39 View Post
                              ... If you have big boat syndrome you need the bigger 5.7 anyway so why keep patching the 5.0?
                              Exactly.

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