Ok so I was given a almost complete engine out of a friends shop. It was there when he took the building over so he does not know why it was pulled out. The markings on the side say 4.0 6-20-87 now the question is if the long block can be saved whould it work in a 97 xj and would it be better to use the intake from a 87 or the 97? I have started to take it appart to check the head and then the bottom end just trying to see if it is worth the effort to have a rebuilt longblock around just in case. Thanks.

 

Use the head and intake from the 97. The 87-90 engines used an EGR valve, you don't want that. The block is really the only thing you should consider using.