View Full Version : 4.0l head...

10-17-2010, 05:03 PM
Hey Jeep guys. I'm working on an '89 Comanchee with a 4.0L; I think there's a burnt valve. I'm planning on swapping the head with a used one and I'm wondering what years of heads are compatible with an '89 block? Thanks in advance for the info!

10-17-2010, 05:26 PM
87-90 Is Renix and a direct replacement for yours.
91-98 HO's will "work" but the intake ports are redesigned and are not a perfect match for your intake.
99-06 is a complete redesigned head and will not work without major modifications, also the early versions of this head (up to 02 IIRC) had problems with cracking

10-17-2010, 05:30 PM
Cool, so when you say it would "work" to use an HO head, what are the issues with it and mods needed? How much is gained by using an HO head?

10-17-2010, 05:35 PM
No mods necessary. Renix intake and gasket will seal but the port shapes are different and any gains the HO head would make will be negated by the disturbed air at the transition from intake to head.

Side note . . . the gains of the HO to the Renix was as a complete package not just the cylinder head. Different cam profile better electronics and a better ECU and programming

10-17-2010, 05:38 PM
Good to know. Thanks a lot! I'll look for a '87-'90 head.

10-17-2010, 05:47 PM
i got one of my xj darren if ya want, its still on the motor, cheap,

10-17-2010, 06:07 PM
I'll PM ya.

10-17-2010, 06:55 PM
Pm back :D

10-21-2010, 07:51 PM
Sooo...I'm waiting for u to let me know if u need this cause it's sitting there waiting to goto scrap dood,

10-22-2010, 10:40 AM
Ya, sory Nick - I forgot to get back to you...
Turns out the bottom end is questionable too so we're waiting till spring to find a donor vehicle unless he finds a drivable XJ with a good driveline for the winter.