4.0 Head on a 258


update: I finally fixed the pics. they were in cmyk instead of rgb
There are several articles on doing this conversion. I'm not going to rehash what they cover. This is simply my take on this mod Be sure to check out:
Tim Weavers article
Tony Carricaburus article

Why?

We're talking about a 40-50hp gain for this mod. Not too shabby given the cost.My old 258's head was burning quite a bit of oil. Much more than should be there from just rings, especially given that I still had decent compression. My other reason is simply that the old valve cover leaks oil in amazing quantities. $100 to get a replacement or $100 on a used head that gives me 40hp. Not a hard decision.

The details

I found a used 1994 4.0 HO head for $75 at a recycler. This head is in excellent condition. I also picked up a valve cover for $10 and got a used cherokee header for $10 at the Upull. There are a few issues with swapping this head on.
1 - The 4.0 head has extra water jacket holes. Some fill these with epoxy and some don't. I'm not going to since the felpro gasket I got doesn't even have holes for them.
2 - The intake will sit higher up than before. The power steering bracket won't be very happy about it.
3 - The stock intake manifold doesn't quite clear the header that I got. To fix this I beat on the header a bit with a hammer.
4) the washers don't line up on the intake where they used to since it's higher. I made some more out of 1/8" x 1" steel flat.

Here you can see where I had to beat on the header a bit for clearance. I went to the upull to try to find an intake that would clear, but all the ones they had wouldn't. The only thing that clears these easily are the stock 4.0 intake manifold for MPI. I'd go that route, but I don't want to spend $500 on the parts to make it work. I didn't grind down the intake since I'm fairly sure the water jacket is right there and the walls aren't all that thick.

These are the washers that I made. 2 of the stock washers work find on the intake and the header. The three that only hold the header of course work just fine.