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  • Fuel Injection Conversion

    Howell TBI ??? Mopar MPI ?$?$? The Mopar kit is supposed to be stock parts from a 94 Jeep right?? Has anyone stripped the parts from a 94 jeep and converted a 258?
    I have a brand new (rebuilt) 258 and do not want to change the head. Will the 4.0L intake fit or can it be modded to fit the 258? The Mopar kit must have an intake that fits, was it a stock manifold that was modded? What about the wiring? Too many questions

  • #2
    Why don't you want to change the head??? A 4.0 head on a 258 is supposed to gain you 40 horse!!! All that is needed to do this swap is to either JB weld or actually weld some water jackets. I really want to do the head swap.

    Good luck



    • #3
      If I change the head to a 4.0L(the 258 head was just rebuilt)then I need exhaust work too


      • #4

        Lots of people do the "junkyard" FI upgrade. There is a plethora of inforamtion on the web about this kind of thing ( has a whole forum for 4.0L swaps, head swaps etc. and is full of knowledgable people that can give you the answers you are looking for). As for the head swap, why not get the most out of a fresh rebuilt 258? The cost is minimal (and could be offset by selling the rebuilt head on the engine now). If exhaust work is the main reason for not doing it I say you must need exchaust work already because you must have inhaled too many fumes !


        • #5

          Last edited by scr83jp; 05-05-2006, 05:50 PM.


          • #6
            The Mopar kit comes with a intake manif. the wiring is easy a new harness is supplied. The kit has good instructions and a tech support phone #. DP


            • #7
              I did the Mopar FI kit conversion and it was worth every penny!!! Did it several years ago so the cost wasn't what it is today. I had more than 220k miles on my 258 and it was like getting a new engine there was such a diff in power!!! Convert to a 4.0L head and don't think twice about it! The best thing you could do!


              • #8
                My brother-in-law has a junkyard MPI kit on his 86, that I made work (felt sorry for him and I enjoy challenges). Anyway, I reworked the factory harness (the yard guy hacked the shot out of it) modified the manifold to work with the 258 head and even labeled all the wires so he could hook it up himself. It really wasn't that tough.

                To modify the intake, get yerself an extra set of intake gaskets (hey youll need one anyway) and line the intake port holes up with the manifold. At that point you should notice that the dowel pin holes on the manifold don't line up, but everything else does. tape the gasket in place, then mark the dowel pin holes with a lead pencil. Take the gasket off, then center-punch and drill the new holes.

                The next step is only required on certain exhaust manifold setups.

                Using a hacksaw, sawsall grinder etc. cut away most of the webbing between the fuel runners. Remember to leave the threaded mounting holes for the throttle cable and what not. Sometimes it helps to have the exhaust manifold bolted to a head so you can test fit the intake to know when you can stop, or you can do what I did and take all the webbing out and say to heck with it.