WHAT HEAD IS THIS?

I've been using the search feature, and haven't found this answer. I picked up a cheap 4.0L out of a cherokee that caught fire. I pulled the head off, and had it hot tanked, and rebuilt. I haven't rebuilt the bottom end yet, but was hoping there would be somebody who could tell me how to identify A) If this is the "HO" head, and B) What year/year range this motor is from.
(It came out of the machine shop very clean, I was amazed...so if there's a mark/stamp/serial number I should look for, I'll be able to find it.)

thanks for the help.

Check the manifold side of the head, up top, about halfway back (I think.)

Casting numbers used for AMC242 cylinder heads...

#2686 - 1987-1990. Also called the "RENIX" head - all exhaust and intake ports are also on a common centreline, and there is a drilled/tapped hole for a coolant temperature sensor driver's (manifold) side rear.

#7120 - 1991-1995. First generation "HO" head, also the "OBD-I" head. Intake ports are raised from their locations in the #2686 (by about 5/8",) and there is still the drilled/tapped hole for the temperature sensor.

#0630 - 1996-1999 (XJ) 1998 (ZJ/TJ). Second generation "HO" Head, introduced with OBD-II. NVH refinements to casting, and there is no drilled/tapped hole for the coolant sensor.

#0331 - 1999 (ZJ/TJ) 2000 (XJ). Last of the "HO" Heads (and AMC242 heads in general - 2007 is the last model year for the 4.0.) Readily distinguishable by drilled/tapped bosses on the spark plug side for retaining the coil rail.

Note that the #0331 is the one with "cracking issues" (it's a crapshoot to when or whether it will happen, tho...) and the #0331 casting was, apparently, quietly revised to correct this issue. I don't know what was changed (anyone?) when it was changed (anyone?) or how to distinguish a #0331 from a revised #0331 (Bueller?)

thanks, that's exactly what I was looking for! yeah, it says 2686 on it, so I guess that makes it a 1987-1990. why is it called "renix?"
-also, I bought this motor while I was driving an '89 pioneer 4.0, but now I drive a '91 sport 4.0L HO. is this head/motor worthless to swap into my jeep?

When AMC released the XJ, it had an engine management system designed/spec'd by RENault, and built by bendIX/king. RENault + bendIX = RENIX.

This was replaced for 1991 with the Chrysler SBEC/SMEC controller and brought up to OBD compliance (a step backwards, y'ask me... OBD was spec'd by CARB, and I've not known California to get ANYTHING right in the last 30 years or so...) and updated again for 1996 for OBD-II (which was devised by SAE, standardised by SAE, and I consider OBD-II an incremental improvement over RENIX. But only just.)

One of these days, I've got to get that casting number page I'm thinking of written and posted...

Through a bunch of reading I found this thread with the head casting #’s. The head casting # on my ’89 mj is 0682 which is not listed. I believe this may be the casting # for a ’97 TJ head. It does not have the drilled/tapped temp sensor hole in the rear of the head and the sensor wire is dangling there unconnected.

My mj is supposed to have a ’97 TJ motor and head with all the renix stuff according to the po. I have been trying to id everything just to confirm this and make sure there is not an intake leak between the renix intake manifold and the ho head. It keeps coming up in searches that the renix intake manifold doesn’t fit a ho head because of 5/8” raised ports.

I’m not too sure about a misfit between the head and manifold. It all looks good to me.

5-90 said:

One of these days, I've got to get that casting number page I'm thinking of written and posted...

Click to expand...