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VP 5.7 GL caruburetor swap to 4 barrel?

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  • VP 5.7 GL caruburetor swap to 4 barrel?

    New thread and I apologize for bringing up the old one.

    I've got a 1997 Cobalt 200 with Volvo Penta 5.7GL PLKD motor and DP-S 1 out-drive... Counted the intake bolts and it's a first gen SBC. Obviously the Vortec is a superior head design and as such a better power plant, but given that mine's a 350 should a 4bbl swap be something to undertake? I have no desire to swap engines (or heads) at this time because it's all original and low-time.

    I've looked at the specifications for the 5.7GL vs the 5.7GS and see a 215HP v. 250HP for the two. I have the shop manuals, which includes both power plants, but it only shows that the GS has a 4V carburetor vice the 2 on the GL. I have googled far and wide for any other differences between the two engines and really can't come up with anything other than carb and hp rating.

    Boat has been dormant for a very long time and rather than rebuild the carburetor I was thinking about doing a swap to a four barrel. Earlier posts suggest that the Holley 4175 might be a good option, at least in the thread for the Vortec 5.0 that I should've left dead.

    Looking at the parts catalog for my 5.7 liter engines model "LK" it looks as though the intake is shared between the GL and GS.... I'm assuming Volvo used a common one with an adapter like they did with the Vortec motors. VP 5.7GS calls for a P/N 3855279-0 Carburetor assembly... as far as I can tell, that's a Holley 4175 based on my googling but much of that is just based on advertising being bumped to the top.

    Thanks for any input from the gray beards (or any slick-faces that happen to know). I'd sure like to go from 215HP to 250HP if it's a simple carburetor swap.

    PS, again I can't tell a difference between the GL (limited power) power plant from the GS other than carburetor. Page 5-35 from the workshop manual gives same specs on cam, rocker arm ratio, base timing etc...
    '97 cobalt 200

  • #2
    Ayuh,...... As you've discovered, the difference is the carb,......

    Go for it,..... You'll "Feel" the difference 35/ 40 hp makes,.....

    Comment


    • #3
      If what you have is actually a GM cast iron 4bbl spreadbore intake (there may be an adaptor for the 2bbl you can remove) then the Holley 4175 will fit perfect because its a spread bore carb, no adapter will be needed and because Volvo also used this carb the throttle hook up should be simple.
      1988 Four Winns 200 Horizon
      4.3 OMC Cobra

      98 Jeep Grand Cherokee 4.0 Selectrac
      07 Jeep Grand Cherokee Limited 5.7 Quadradrive II

      "While air doesn't freeze....rust never sleeps"

      Comment


      • #4
        Gentlemen, thankee much for the input. As far as I can tell the manifold is common between the two power plants. As of material I'm not sure, but based on the newer Vortec that was aluminum with brass coatings... that being the 8-bolt. Just my guess, mine is iron (magnet store is my next stop). In the parts catalog for the 5.7 "LK" engines it does in fact specify a carburetor to intake manifold adapter (P/N 3853278-4). I can find no information on the specs for this plate or what I should use as a non-VP substitute.

        Thank you again very much. I do plan on doing the swap. At least with the larger displacement of the 350, I'd expect that it could use the 650CFM carb at least to 75% at 4800 RPM just based on the basic math.
        '97 cobalt 200

        Comment


        • #5
          http://www.volvopentastore.com/Fuel-...view_id.780887
          fuel system

          here it shows the 4160 style carb (square bore) with the adapter plate, they may have changed from the spread bore 4175 at some point..
          I find VP catalogs maddeningly complex and confusing with the plethora of model numbers etc, best bet is take a good pic of what you have.
          If you have a GM 2bbl manifold then you have to get the right intake for the 4bbl
          If you have a GM 4 bbl manifold with an adapter for the 2bbl carb, then remove that adapter, and you can likely use either a spread bore Holley (4175), with no adapter or a square bore Holley (4160) with the adapter shown in the VP catalog.
          1988 Four Winns 200 Horizon
          4.3 OMC Cobra

          98 Jeep Grand Cherokee 4.0 Selectrac
          07 Jeep Grand Cherokee Limited 5.7 Quadradrive II

          "While air doesn't freeze....rust never sleeps"

          Comment


          • #6
            Wilco good sir, I'll report back when I pull the carb and see what I've got! Thanks again!

            '97 cobalt 200

            Comment


            • #7
              I did the 2bb to 4bbl on my 2002 5.7, using the Holley 4175 650 spreadbore. My engine is a Vortec, and VP did put a very nice 4bbl intake with an adapter for the 2bbl. I gained around 500 rpms. The smaller Primaries of the Spreadbore will help retain Torque at the bottom end as you will probably have to increase Pitch to keep the engine within the WOT range after switching to the 4bbl.

              Comment


              • #8
                Jimmbo you've sold me, but there's a curveball... My engine for absolute certain has an intake manifold that does not have an adapter... it will only support a 2V carb... the VP parts catalog was untruthful

                I'm bummed, but i'm still for sure going to do an upgrade. I guess the question now is what intake manifold do i choose? I"m contemplating the edelbrock 2506

                https://www.michiganmotorz.com/edelb...87-p-3761.html

                and still thinking about 4175 b/c thats what VP used. Though I did just happen upon an interesting Holley solution: the Holley Sniper EFI quadrajet. No more vapor lock on super-high ethanol california gasoline! If only money grew on trees!


                '97 cobalt 200

                Comment


                • #9
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                  Would recommend the regular performer vs the performer rpm you sent a link to. https://www.michiganmotorz.com/edelb...87-p-3262.html

                  rpm range for the performer is idle to 5500 vs the 1500-6500 for the performer rpm. The link you posted had conflicting rpm ranges in the text and specs below... I’d just make sure you are getting the performer with the parts combo you have

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