4.0 FI on a 4.2?

[Chris S]

A buddy can get an FI 4.0 out of a YJ that has a cracked block. He was wondering if it is possible to use the bits from the 4.0 to give his CJ Fuel Injection?

[CU4WHLN]

YES !

That is exactly what I did. Took the 4.0L head and stuff off a 94 XJ.... Used a 94 YJ engine harness... (wires sucked).... change that timing chain!... installed a 4.0L cam-you must use 4.0L pushrods if you do this,don't have to change the cam..... used the Mopar instructions and pictures to figure out all the parts included in the kit. You need the harmonic balencer from Mopar... and some fab skills....bolted it together.... MPI 4.2

Very happy with the result.

['76CJ5]

Thank you for replies like this. I would of never thought of the pushrods. I hope to make this conversion someday also.

[Chris S]

So we just need the "top end" from the 4.0, the computer, the timing chain, and the harmonic balancer?

Do I understand correctly that the 4.0 cam and pushrods are optional??

[CU4WHLN]

Yea.... just take the top end. I did the cam because I was thinking an EFI cam profile would match the system.

Change the chain because I have yet to see a stock one fair very well... makes the Jeep run badly as it's so sloppy it affects timing.

The wiring.... ah.... that **** wiring....

Better be ready to do some serious frustrating work there. Maybe a better route would be to buy the Mopar harness from Hesco?? I'm pretty good with wiring (OK, my friends helped A LOT !) and it drove me/us crazy for 6 weeks. Still, way cheaper though !

The damper is required to relocate the CPS signal for the computer. I made my own mount, and bought the sesor. It helped that I could look at my buddies Mopar MPI setup.

Overall, one of the best things I have ever done to the CJ....

Oh yea... use either the 258 pushrods and lifters OR the 4.0L pushrods and lifters. The stack up height is the same, but each is matched. Either will work OK.