Dave1123,
I'd love to replace that head... it's not in the cards right now but eventually when I do pull that head off it will result in a complete engine rebuild, may as well, I'd like to replace all of the seals and update a few things to make sure it's truly bulletproof like the 4.0L is supposed to be.

 

You can go to a pick an pull yard and get a head off a 2004 grand cherokee they have 0331 tupy head I got one of less then $100 and just checked all the valves and reseated them then installed new valve seals , been running the head now for about 4 months with no problems . It cost me more for the gaskets and bolts then it did for the head .

 

Thanks Tech, that's a good option. I need to figure out to do with my valve cover. It seems that I have a 1991 block, 2001 head, 1991 valve cover. If I go to a pick and pull yard I may just look for a 1991 head. Then I need to deal with whatever modification was done to the exhaust pipes to mate with the 0331 head. What a mess this has turned out to be. All I wanted to do was stop it from leaking oil from the valve cover, is that too much to ask. Some dummy did a number on this engine.

 

If you have 2 small exhaust manifolds with 4-02 sensors and 2 cats I think you will need to stay with that setup because those manifolds will not fit a early head . I don't think they make a exhaust manifold adapter .

 

No, in his pics he has an exhaust adapter and a steel tube header like a 91 should. The only way to tell for sure which engine it is is from the block number molded into the side of it between and below the first 2 freeze plugs on the driver's side. Besides that, even though the 00-01 used the 0331 head, the block was still the old style with an oil filter adapter. The WJ block has the filter screwed directly into the side of the block on the lifter oil gallery.

You really need to know what block you have because to may have head locator dowels. The 91-95 7120 head doesn't have holes for them and the 96-99 0630 head does. Also the 0630 head has a paired center exhaust port and no center manifold mounting bolt. You can grind down or remove the locator dowels if need be. The 7120 also has the new valve cover design.