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1990 vs 1992 4.3 block swap

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  • 1990 vs 1992 4.3 block swap

    I have a 1990 4.3 non balance shaft maercruiser with the 2bbl carb and fluid mounts. I found a 1992 4.3 automotive engine from an s10 for $50. I would like to have a backup maybe something to work on over the winter. I know I can only use the head and block with crankshaft the intake should still be the 12 bolt right? Does the balance shaft pull horsepower? I know the cam should work. Change tje freeze plugs.
    any other things to consider? I have the mechanical fuel pump. Does that still work?
    https://forums.iboats.com/forum/engi...4-3-block-swap

    1990-4-3-century-2000-floor-transom-stringer-upholstery-project

  • #2
    Will there be a problem with the flywheel from a non balanced engine to a balanced engine? I think the non balanced engine had sone counterweights on the flywheel. Will this give me trouble
    https://forums.iboats.com/forum/engi...4-3-block-swap

    1990-4-3-century-2000-floor-transom-stringer-upholstery-project

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    • #3
      either stick with the same generation, or change everything. DO NOT try to mix and match rotating components... that viper will bite you in the back side.

      heads, intake, exhaust are the same, however everything in the short block is different, including the engine mounts

      here is some reading on the 4.3

      https://forums.iboats.com/forum/engi...asting-numbers
      Cheesehead boating the Gulf Coast of FLA 27.51° N, 82.53° W

      1988 Cruisers Rogue 2420 -VP 290 DP now powered by custom 468 - https://forums.iboats.com/forum/owner...988-rogue-2420

      Past Boats
      1970 Wooster Hellion - Merc 9.8
      2002 SeaRay 190BR - 5.0 - A1G2 - "Cheeseheads in Paradise"
      1984 Avanti 170DLI -3.0 stringer- "Ship Happens"

      What’s behind you doesn’t matter.Enzo Ferrari

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      • #4
        I see that the only difference is that 1992 has the balance shaft. That is better anyways, right. So I can install the mercruiser camshaft and change freeze plugs and seals and have a marine engine.
        https://forums.iboats.com/forum/engi...4-3-block-swap

        1990-4-3-century-2000-floor-transom-stringer-upholstery-project

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        • #5
          The fluid mounts should still work with a balanced engine. The manual #7 is good until 1993
          https://forums.iboats.com/forum/engi...4-3-block-swap

          1990-4-3-century-2000-floor-transom-stringer-upholstery-project

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          • #6
            thats because in 1993 they were still using motors left over from 1991 and 1992

            no, the difference between the balanced and non balanced is significant

            damper is different, flywheel is different, cam is different, block is different, timing set is different, timing cover is different.

            because the damper and timing cover is different, the accessories - specifically the accessory drive brackets and pulleys on the front of the motor are different.

            when they went to the balance shaft motors, the damper, flywheel and mounts became common with the 5.0 / 5.7 motors
            Cheesehead boating the Gulf Coast of FLA 27.51° N, 82.53° W

            1988 Cruisers Rogue 2420 -VP 290 DP now powered by custom 468 - https://forums.iboats.com/forum/owner...988-rogue-2420

            Past Boats
            1970 Wooster Hellion - Merc 9.8
            2002 SeaRay 190BR - 5.0 - A1G2 - "Cheeseheads in Paradise"
            1984 Avanti 170DLI -3.0 stringer- "Ship Happens"

            What’s behind you doesn’t matter.Enzo Ferrari

            Comment


            • #7
              I will echo Scott. Rotating assemblies must be matched.
              17 Foot '90 Bluewater
              Alpha 1 3.0 Merc - repowered in 2016
              now - 4.3L Vortec - Alpha 1 GenII
              Honda BF100L kicker
              Engine custom - Transom 0D65328 - Drive 0D648864
              If you ain't fishin, then yer working too much.

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              • #8
                I asked the seller for the c/n to be sure. but sounds like there are just too many variances to make it work correctly. thanks for the help. I guess i'll stick with 87-91 models
                https://forums.iboats.com/forum/engi...4-3-block-swap

                1990-4-3-century-2000-floor-transom-stringer-upholstery-project

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                • #9
                  Also you need to get a different oil pickup, oil pan, camshaft has different lobes in automotive engine vs. Mercruiser. All gaskets must be marine instead of the automotive. In 1993 they also changed the fuel pump from mechanical to electrical, so newer block with balanced shaft might require you to get a new fuel pump. Distributor must be also marine and not automotive. these are just a few differences I can think of on the top of what the other posts said.
                  1998 Ebbtide 210 Campione, Mercruiser 5.0 V8, 1993 Larsen Sei 200 BR, Mercruiser 5.0 V8 1990 Bayliner 2050, Mercruiser 3.0LX 1984 Mercedes, OMC 3.8 V.6

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                  • #10
                    I would have just used the block and heads as a short block assembly. everything else will come from the old block. Combined with a mercruiser rebuilt kit should have given me a marine engine with balance shaft.
                    https://forums.iboats.com/forum/engi...4-3-block-swap

                    1990-4-3-century-2000-floor-transom-stringer-upholstery-project

                    Comment


                    • #11
                      Originally posted by Chris51280 View Post
                      I would have just used the block and heads as a short block assembly. everything else will come from the old block. Combined with a mercruiser rebuilt kit should have given me a marine engine with balance shaft.
                      No it wont. your not understanding

                      your short block assembly is the Block, crank, rods, pistons, cam, balancer, timing assembly, flywheel.

                      that all must remain together. you cant mix and match parts.

                      and because the timing cover changed and the balancer changed from GM, Mercruiser had to change the accessory drive when they went to a balance shaft motor.

                      only the heads work on either block until 1995

                      either stick with all components from a non balance shaft motor which means get a different shortblock or rebuild the one in the boat now

                      or switch everything over to the mercruiser parts for a balance shaft motor which means getting all the stuff to bolt on the balance shaft short block to make it a mercruiser - accessory drive pulleys, brackets, belts, manual transmission flywheel for a balance shaft 4.3, cam would be close enough to use.
                      Cheesehead boating the Gulf Coast of FLA 27.51° N, 82.53° W

                      1988 Cruisers Rogue 2420 -VP 290 DP now powered by custom 468 - https://forums.iboats.com/forum/owner...988-rogue-2420

                      Past Boats
                      1970 Wooster Hellion - Merc 9.8
                      2002 SeaRay 190BR - 5.0 - A1G2 - "Cheeseheads in Paradise"
                      1984 Avanti 170DLI -3.0 stringer- "Ship Happens"

                      What’s behind you doesn’t matter.Enzo Ferrari

                      Comment


                      • #12
                        Thank you Scott. Was about to get the wrong engine.
                        https://forums.iboats.com/forum/engi...4-3-block-swap

                        1990-4-3-century-2000-floor-transom-stringer-upholstery-project

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                        • #13
                          Scott Danforth I found another 1987 block which I will confirm the block casting numbers. Its an automatic. Is this a problem?
                          https://forums.iboats.com/forum/engi...4-3-block-swap

                          1990-4-3-century-2000-floor-transom-stringer-upholstery-project

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                          • #14
                            the block doesnt know what the crank has bolted to it

                            however with a 32 year old block, you have about $700 in machining (cleaning, line-hone, decking, boring, honing) prior to assembly

                            Cheesehead boating the Gulf Coast of FLA 27.51° N, 82.53° W

                            1988 Cruisers Rogue 2420 -VP 290 DP now powered by custom 468 - https://forums.iboats.com/forum/owner...988-rogue-2420

                            Past Boats
                            1970 Wooster Hellion - Merc 9.8
                            2002 SeaRay 190BR - 5.0 - A1G2 - "Cheeseheads in Paradise"
                            1984 Avanti 170DLI -3.0 stringer- "Ship Happens"

                            What’s behind you doesn’t matter.Enzo Ferrari

                            Comment


                            • #15
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                              I was just wondering since the unbalanced engines were tested and balanced at the factory. Drilled at the dampener and or flywheel. As long as I keep the rotating parts together. Like you said.
                              I wasn't planing on doing a complete overhaul. just rings and bearings if needed. New oil pump
                              https://forums.iboats.com/forum/engi...4-3-block-swap

                              1990-4-3-century-2000-floor-transom-stringer-upholstery-project

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