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    Replacing heads-gctid373561

    how much more is it to replace your heads w an upgrade than to have yours redone? Anybody have a clue here.. nows the time for me to do it...

    #2
    There will many choices.

    Remember that any change to cylinder heads may affect your piston selection, and visa-versa.

    Perhaps you could read Andrew's thread also. You and Andrew look like you're both wanting to do similar.

    Andrew would be able to build a bit more power into his, as the Merc drive is at it's limit near 300 hp and/or up to 26 foot hulls, as per what you'll read.

    .
    Rick E. Gresham, Oregon
    2850 Bounty Sedan Flybridge model
    Twin 280 HP 5.7's w/ Closed Cooling
    Volvo Penta DuoProp Drives
    Kohler 4 CZ Gen Set

    Comment


      #3
      Bounty, my hull from factory is 27.5... why would they have paired me at the max from the get go?

      Comment


        #4
        Ive read the max hp is at or around 300 on my drive.. could i go above that and just take it easy on the hole-shot and be fine? with this opportunity id really like to be able to hit 35-40mph if needed. ya know?!

        Comment


          #5
          can i port and polish the heads to achieve the torque of the quench build and the speed i desire?

          Comment


            #6
            im learning too and we have almost the same boat why do u need this speed with today gas $$$$.

            i don`t think that u are going to race. 60mph on the water is like over a 150 on the road

            have fun cruising and bbq

            im not going to put my 280 up to limit

            check this

            http://www.boatdesign.net/forums/pow...elp-32141.html

            Comment


              #7
              apexaro1 wrote:
              Bounty, my hull from factory is 27.5... why would they have paired me at the max from the get go?
              I can't answer that. Perhaps the deal that B/L cut with Mercury Marine...... perhaps not making the right deal with Volvo Penta....... perhaps marketing..... perhaps who knows??

              Many of these older Vicky's were Volvo Penta, and there are no issues with more hp, if within reason.

              apexaro1 wrote:
              can i port and polish the heads to achieve the torque of the quench build and the speed i desire?
              The quench increases low end torque, and for several reasons. Less detonation potential, slight increase to C/R, and more spark advance can be used.

              andrew 1 wrote:
              1.... im learning too and we have almost the same boat why do u need this speed with today gas $$$$.

              2.... im not going to put my 280 up to limit

              3... check this

              http://www.boatdesign.net/forums/pow...elp-32141.html
              1.... More speed gets the hull up and out of the water further. Anytime that we can do this, we reduce hull friction.

              Planing is one thing... but getting just above planing attitude helps greatly.

              2... No... the 280 (if good) will handle the added power. No issues there!

              3... I think that the last guy who posted (Erik) is mistaken. (see #1 above).

              Also note that they're talking about a 23 foot boat.... not a 27 foot SDN F/B boat!

              **************************************

              I've known and have been aware of many 2750 Victoria SDN F/B owers over the years. Most were Volvo Penta since that's what I'm involved with.

              Of these owners, some went to the Duo Prop lower unit. The Duo Prop did more for these hulls than any increased horse power did with a single prop drive.

              Of course the Merc 260 drive (the predecessor to the A drive) can't be made into a Duo Prop, but any of the Volvo Penta drives can be.

              I've also swapped a few of these from Merc to Volvo Penta so that the Duo Prop could be used.

              I'm not suggesting that this is the only cure....., just mentioning it as an option.

              .
              Rick E. Gresham, Oregon
              2850 Bounty Sedan Flybridge model
              Twin 280 HP 5.7's w/ Closed Cooling
              Volvo Penta DuoProp Drives
              Kohler 4 CZ Gen Set

              Comment


                #8
                A set of race heads cost depndimg on who they come from and what type you a buy. Edelbrock performer rpm heads can be found for around $1000.

                Ededelbrock also sells more expensive heads. Brodix heads go for alot more.

                Now when buy heads getting a race head up doesn't necessarily mean buy what flows the most. You aren't building a race engine just using some race parts. You will never run at high rpm or smokem off the line. Infact the bigger the head to a point loses low end torque so you have to be careful.

                A $1000 edwlbrock head works break. Forget about porting and polishing. Todays technology is way past that. If you pair a edelbrock rpm manifold to a rpm head with the right piston and the cam you will have a torque monster and beanie to realize about 10mph faster. Now keep in mind that what you so to the intake side you have to do to the exhaust side. Outdrive exhaust is very restrictive. To claim full use of the newly built power you will need to rework the exhaust. Not such a easy thing on outdrive exhaust.
                1989 Avanti 3450 Sunbridge
                twin 454's
                MV Mar-Y-Sol
                1979 Bayliner Conquest 3150 hardtop ocean express.
                Twin chevy 350's inboard
                Ben- Jamin
                spokane Washington

                Comment


                  #9
                  My pre-vortec head had a crack in it, so I upgraded to vortecs (new from Michigan Motorz). All I had to do was reassemble with a new intake manifold (for the vortec) and gaskets and gained 500 rpm at WOT. The chamber size was the same between the old and new heads, so I didn't have to screw around with anything else.

                  Comment


                    #10
                    "The chamber size was the same between the old and new heads"

                    Leedub, that statment is not correct; Vortec heads have a smaller chamber size then pre vortec heads.

                    Vortecs are 64cc most 87-96 350 non-vortecs are 76cc

                    Leedub is correct on you will need a intake and heads if you want to change over to vortec heads.

                    Comment


                      #11
                      Jamesfast wrote:
                      "The chamber size was the same between the old and new heads"

                      Leedub, that statment is not correct; Vortec heads have a smaller chamber size then pre vortec heads.

                      Vortecs are 64cc most 87-96 350 non-vortecs are 76cc

                      Leedub is correct on you will need a intake and heads if you want to change over to vortec heads.
                      My non-vortecs were 64cc for sure. Not sure if 64cc was the norm or not, but that's what I had.

                      Comment


                        #12
                        There will be quite an array of combustion chamber volumes through the years. ( 58, 60, 64, a rare 65 I believe, 70, and 76cc )

                        If you have any questions about your cylinder heads and chamber volume, do a search for Small Block Chevy casting number web sites....., and go to the cylinder head section.

                        Not all sites will list all chamber volumes, so keep trying different web sites.... you will eventually find what you're looking for.

                        The Martec site was great, but seems to have been taken down.

                        Not all sites use routine columns as a means of organizing and identifying volumes.

                        You may also see intake runner volume and exhaust port volume being shown.... so don't get confused between these.

                        You will also see that some sites list heavy -vs- light castings.

                        I believe that we may find some mistakes, so I'd suggest that you look at more than one web site.

                        .
                        Rick E. Gresham, Oregon
                        2850 Bounty Sedan Flybridge model
                        Twin 280 HP 5.7's w/ Closed Cooling
                        Volvo Penta DuoProp Drives
                        Kohler 4 CZ Gen Set

                        Comment

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