I am aquiring a lifted xj with a built 4.0 including supercharger.

however he never changed teh oil or didn't chack it and teh engine is now blown (I have no idea which part)

I can get a free good running 4.2 that I can throw in while I rebuild the other. What steps are involved in this? going from fuel injection down to carbed? anybody do this?

why bother, just get the 4.0 running and be done with it.


now a 4.0 head, on the 4.2 bottom end with the supercharger, now that would be an interesting idea. (hint, hint)

would be torquey as hell.

I was thinking about that but I really need a running vehicle.....

so I am thinking about running the 4.2 as a temp.

besides, like I said, this motor was BUILT. I am not sure about teh specifics but it had crank and a bunch of other stuff done to it...

Keep the fuel injection. It would be easier than taking it out. All you would need is a new/old exhaust manifold. Otherwise you be doing major re wire, or really basic carb w/ no smog.

Put the block and all the parts (alt., water pump, power steering) in and use the intake manifold from the 4.0. It should bolt up using the alternate bolt configuration.

If the head is not toast, then this is the best of both worlds. Just pull the motor, swap bottom ends and stick it back in.

Sounds simple to me, but that means it will be a ton of work.

I am a little confused about what you just said...I know the 4.2 block w/ a 4.0 head works great......but you're saying that the 4.0 intake and exhaust manifold will bolt to the 4.2 head?

if that is the case than this can be a one day job to drop in the new motor while I wait to rebuild the old motor.......or just sell the old motor for $$$$$$ and recoup almost all costs.

Originally posted by mkbruin
I know the 4.2 block w/ a 4.0 head works great......but you're saying that the 4.0 intake and exhaust manifold will bolt to the 4.2 head?


4.2 and 4.0 intakes can be interchanged between the two head styles (with careful allignment).
You must, however, use the correct style exhaust manifold that matches the head.
Example: 4.2 block + 4.0 head + 4.0 exhaust + 4.2 intake is OK.
4.2 exhaust + 4.0 head is NOT OK.

ok, so I could possibly run 4.2 block + 4.2 head + 4.2 exhaust manifold + 4.0 intake?

this sounds like a cheap, easy way to get this jeep running again while I rebuild the built engine.

everything with the computer, FI, and wiring would be ok?

Yeah pretty much.
I think you will want to get your hands on the MPI installation instructions, since that is basically what you are doing. One benefit is that you have all the wiring done already.

You will need to swap some parts too. You want all the ignition from the 4.0. So you will pull the distributor and the coil off the 4.0 and put it on the 4.2. But you will need to block off the fuel pump hole on the 4.2 block. That is where the MPI kit mounts the new coil.

Don't sell the old 4.0 motor. You'll at least want the head if not the whole block. Unless you want to sell me your 4.0 head and exhaust manifold.. ;) You may find the 4.2 pings with fuel injection. The fix is being talked about on the page right now. The only thing that I have heard that works is a 4.0 head.

I really suggest pulling the 4.0 and taking a long look at the head. If it is good, then have the water ports blocked off and put it on the 4.2 while every thing is out.

I do not know if he blew the head or the block.....if he messed up the block, I am going to swap the head onto the 4.2 block. I have no idea what happened here other than a little over a year ago this engine was put in with all the right go fast goodies....

NO!


this is what you would want to do:
run the 4.2 block with the 4.0L head, 4.0L intake manifold, and 4.0L exhaust manifold.

the block should almost bolt in. i think you may have to get a different bolt for one of the engine mounts...

you'll have to follow the 4.0L head swap onto a 4.2L rules. look at this:

http://monsterslayer.com/jeep/40Head/40Head.htm

ideally, you should get the torque of the 4.2L and the Hp of the 4.0L. i almost did this to my 1988 Comanche, but it wasn't an HO.

matt

Isn't that what he said:confused: