forgive me if engine building isn't considered "hardcore tech" but at any rate, I'm sure I'll get a better answer here.

I'm building a 4.2 with a 4.0 head. I understand there are different casting numbers for the head and I need to know which one I should look for and why. also need suggestions for a slightly better than stock cam. also, for my motorcraft 2100, should I go with the 1.08 venturi size or 1.14. I'm starting with a stock 1983 shortblock assembly and will go with the stock xj 4.0 header but later on, an aftermarket one. stock 4.2 intake. high volume oil pump and water pump. also HEI distributer

thanks in advance for any help!! I know there's a lot of brains on this site!

Well you're right, not a very hardcore question, at least for this site. Check out this other site, because they have a whole section on this subject.
http://www.cjoffroad.com/

Check this link out. There is some really good info and links to more inside.

http://bustedjeep.com/projects/rebuild.asp

Well motor tech may not be hardcore but it's so much fun!

The best 4.0L head is HO, high output, or 91-95. Some people call it the HI-PO head due to fact that the porting is superior to earlier or later model 4.0L heads.

Interesting fact, they de-tuned the later model heads for emissions purposes (faster warm up) by restricting the ports slightly. In order to maintain the factory power rating Chrysler designed the equal length runner 4.0L intake, found with later model 4.0L engines to compensate.

The Renix heads are garbage.

Can't help you with your carb.

IMO the easiest way to put a cylinder head together for this swap is Clearwater Cylinder Head in Clearwater, Florida (www.cylinder-heads.com (http://www.cylinder-heads.com)). They will sell you a quality hi-po 91' to 95' rebuilt head, ports welded so you don't have to deal with that, loaded and ready to go, shipped, for about $500. It would be hard to beat that if you owned a machine shop, IMO.

I have two in service and know of many more with no problems.

here's another link to them: eBay (http://cgi.ebay.com/ebaymotors/AMC-JEEP-258-4-0-H-O-Conversion-Cylinder-Head_W0QQcmdZViewItemQQcategoryZ33617QQihZ008QQite mZ180157563520QQrdZ1QQsspagenameZWDVW)

edit: to fix the link

As posted above check our the writeup on www.bustedjeep.com. Theres a lot of good info there. As far as the 2100 goes I had the 1.08 venturi on my cj in the past and it ran great, I'd go with that one over the other two.
Kevin

$500 is a bit expensive for a rebuilt head. I purchased a 91-95 head for my 95 4.0 last year on eBay for $230 shipped. The seats were ground from 3 angles. They also decked the head and installed new valve guides and seals. You might be able to get the ports welded and still have money left over. Just another option...

$500 is a bit expensive for a rebuilt head. I purchased a 91-95 head for my 95 4.0 last year on eBay for $230 shipped. The seats were ground from 3 angles. They also decked the head and installed new valve guides and seals. You might be able to get the ports welded and still have money left over. Just another option...

Maybe. Actually I checked the link and it is $425 shipped. Was recommending it more from a "these guys have done tons of these and they are a dependable company with a dependable product at a reasonable price" point of view.

Two in the hand, ya know?

thanks for the help guys!! $425 seems pretty good for a head that's actually rebuilt properly as apposed to just being cleaned and checked, not to mention having the water jackets taken care of to boot! it's not listed on their site, but I'll email them about it.

also, that bustedjeep build is just what I was looking for, a complete motor package to follow!

Also another thing to think about is actually finding somebody to weld the water jackets up for you. When I did this on my 4.2L I had a really hard time finding a shop that would touch it. Ended up my dad knew a shop that rebuilt giant diesel engines and they did it for me, but they said not to tell anybody who did it cause they didn't want to do another, haha.