So i have a head question. I am a student at a technical college and i get the privilege of re-doing a head. I went to a junk yard and pulled a head of a jeep motor that I think was a 4.0. But when it was time to check casting numbers to find valve and seat information for the class i discovered the casting numbers to be all F!@#ed up. A 2685 is a 4.2 and a 2686 is a 4.0. I need a 4.0 head. besides the casting numbers is there any tell tail signs of which head a currently have? I cant go check the jeep i removed it from because it has since been shredded.

 

What jeep was it from? No cherokees came factory with 4.2

 

From what I have seen the 4.2L will have little freeze plugs in between some of the intake and Exhaust ports, and share the center exh port, like this.


and the 4.0L will not have them. Like this...



Also all 4.0's came fuel injected (IIRC) and will have this relief in the head ports for the injector clearance.


Some good 4.0 head info with casting numbers
http://www.enginebuildermag.com/Item...der_heads.aspx

also you will need to know if the engine your planning to use this head in is a Renix, HO, or 2000+ as they all use different Exh manifolds and the ports are cast different.

also if it looked like this its a 4.0l (unless swapped) Cherokee or XJ


If it looked like this it is a 4.2L (unless swapped) FSJ cherokee

 

thank you gorrillaxj that was some really good information. thanks to your pictures and descriptions i now know its a 4.0 head and not a 4.2

 

Moved to OEM Tech since this is discussing OEM parts identification.