Off Roading Forums banner
1 - 4 of 4 Posts
G

·
Discussion Starter · #1 ·
I don't want to belabor this point, but I'd like to check out my understandings before I take the jump. I have a CJ85 258. I plan on putting a 4.0 head on it from a '94-'95 4.0. I understand I will need to block off the coolant ports on the 4.0 that do not match up with the 258 head. I also understand that I will need to get a different exhaust header to match the 4.0 head. Will I be able to use an Offenhauser intake manifold and the 4bbl Holley from the 4.2 head on the 4.0 head or is it set up only for fuel injection? Will I be able to use the cast aluminum value cover from the 4.2 head or do I need to pick up a cover for the 4.0?

What is the practical - useful limit on value sizes that can be installed in the 4.0 head. I believe Clifford lists the 2.02 and 1.75 approximately? Can an OEM 4.0 head be further ported?

I'd appreciate your comments and ideas. Thanks, in advance. MindBender

 
G

·
Discussion Starter · #3 ·
Thanks, it did answer the questions. Appreciate the recommendation. I had a real nice 258 head, but the pedastal that holds the rocker arm broke off. Unusual,huh. So I found another one and was having a machinist port it... Well he went through the water jacket.. Bigtime. I don't see why I would go with a 4.2 head when the 4.0 head is such a match up. However, I am interested in the possibility of the 4.0 head being further ported, but get equally concerned that the machinist will just drill through this one, also. Are there any specifications on the amount of steel in the walls of the intake and exhaust ports? Thanks, MindBender.

 
G

·
Discussion Starter · #4 ·
I know that it can be further ported, but am not sure how much. The one thing I have heard over and over is that it is not something you want done by just anybody. Because of the tighter tolerances, it is best performed by somebody with experience on that head. I know Clifford Performance specializes in this type of work. While they may be too expensive for you, they might be willing to pass along some hints like the specs. you are looking for.

Let me know how it all works out for you.

Good luck.

 
1 - 4 of 4 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top