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  • 4.3 Liter swap

    I have finally decided to ditch the 258 for something with a little more power and better economy. A local shop had a core 4.3 liter chevy V6 lying on the back lot and when I asked about it they said haul it away and it is yours, so I have it lying in pieces on my carport doing a complete rebuild (two spun bearings due to excessive oil chainge intervals).

    The plan is to install the motor with a Gm TBI system built from Yard parts. The 4.3 has plenty of power with the TBI, in fact it has the same rating as a stock 4bbl 350 (160 HP, 230 ft-lb torque, little more than that with a few basic upgrades) Plus the 4.3 gets better mileage, my wife routinely gets 20 mpg in her 4 door blazer in the warmer months (I'm thining the weight difference between the blazer and the Cj will just about make up for the lack of an overdrive)

    Anyway I now have a bell housing from a 151 4 cyl on the way from ebay to mount the V6 to my T4 (untill I can save up enough for a better trany), but I was wondering which flywheel to use, will the standard 4.3 flywheel from like an s-10 blazer work with the 4 cyl bell or do I need to source it from somewhere else?

    Any help would be great.

    Sorry 'bout the long post

  • #2
    I had a problem finding a 153 toot flywheel for a 4.3, so i took the 168 tooth flywheel and had it milled down to fit the 153 tooth ring gear. Only thing is i had my old flywheel off the Iron Duke and i had them match up the holes on the flywheel so everything went smooth.


    • #3
      Hmm, this is interesting, so the standard 168 tooth won't fit in the housing?

      With the smaller flywheel, what starter did you use?

      Did you have to use the smaller 4-cyl clutch or a standard chevy clutch?


      • #4
        It's been a while since I did my Chevy conversion. I used the same bellhousing you are using and the small flywheel. I think I used a starter from a GM inline 6 cylinder 250 CI. David


        • #5
          .....the starter was from an older Nova with a powerglide transmission. I think they have a smaller bellhousing also and can't use the larger flywheel due to clearance problems. I was able to use all of my original clutch hardware. The pressure plate I took out of the Jeep bolted to the GM flywheel. It was an easy conversion and I'm very happy with it. David


          • #6
            i dont remember what i did since that jeep was long gone, but i made a hybrid starter from the original 4.3 and the original jeep one. I hear you can also use a mini high torque starter off a 350 and thatll work, but ive never tried it, i was going for cheap. It was a great swap and the power was great.


            • #7
              Well, I did a little research at work, and I think I tracked down a suitable starter for the swap, a 1980 GMC caballero with the 229 V-6. The 229 is a 90 degree V-6 like the 4.3, and it used a 153 tooth flywheel, so it should be a no brainer to make that work, now it looks like I have to find a flywheel.

              I would like to use either my stock 10.4 inch clutch off the 258, or a 10 inch chevy clutch. Anyone hear of a donor for the smaller flywheel? I would really like to avoid milling down a flywheel if I can avoid it. Mably a camaro with the 305/5.0?


              • #8
                Also 4.3

                I put a 4.3 TBI in my CJ-7. I have a 700R4 tranny so there were no flywheel issues. Motor runs great but seems to lack power. Presently running 31 inch tires and 3.92 gears.


                • #9
                  The 700 R4 is a good trany, but I like a stick in a Jeep.

                  My blazers only seem to be lacking power when towing my camp trailer (2000 lb), and only then on an 8% or better grade, other than that, they seem to have plenty of power. (they are no speed demons or road racers, but they get you where you are going, no problem)

                  I have foubd that my 4.3s really don't like Bosch Platinum 2 spark plugs. I won a free set in a sales contest at work, so I put them in. I lost 4 MPG and I couldn't run faster than 45 with my camp trailer. I put AC-Delco copper plugs back in and my mileage came back and I ran 75 all the way with the camp trailer on back. No other changes. Lesson learned.

                  Back to the swap.

                  the flywheel required is out of a 1990 camaro RS with the 5.0 motor. 153 tooth, and uses a 10.5 inch clutch. Now I just need to track one down