1. 4.2l to 4.0 swap? Your advice needed :).

    Hi guys, I've got a 1989 Wrangler with an AWD automatic transmission. The things got a lot of mileage so I've been thinking about getting a new motor to replace my tired old 4.2l with a 4.0l fuel injected motor and a new awd auto trans and I'd also like to upgrade the rear brakes from the drum units to disc.

    Alright so here are my questions:

    1) Would a newer fuel injected 4.0l motor bolt right up in place of the old one without any modifications?

    2) Would the transmission fit in there properly as well?

    3) Is there a kit out there to swap out the drums and replace'm with discs that don't require any extensive mods..?

    4) Would you buy new parts or junk yard pull-a-parts?

    5) Would I be better off just buying a newer Wrangler?

    6) What do you think it would run me $$$?

    I appreciate the advice, thanks.
    Last edited by wannagojeepN; 06-02-2008 at 07:45 PM.

  2. #2

    Re: 4.2l to 4.0 swap? Your advice needed :).

    I would consider a 4.6L stroker, basically a 4.0L engine with your 4.2L crank. It'll bolt in place of your 4.2L engine. You could also rebuild your 4.2L and add a 4.0L HO head for better performance.

    As for the rear discs, find a rear axle from a '95+ Explorer, it will have disc brakes, same wheel pattern, and can be found with many of the common jeep gear ratios. Can even be found with a limited slip diff, and relatively easy to install.

  3. #3

    Re: 4.2l to 4.0 swap? Your advice needed :).

    I'm having the 4.2 rebuilt, adding MOPAR fuel injection and headers.

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