A friend of mine has a 2000 XKR with a bad engine and I have a 99 XJR parts car with a good engine still in it. Is there a way he can use that engine in is XKR??

I understand the short blocks are interchangeable, and the differences in the (intake ?) cams, but will he also have to swap his heads over to my engine?? Or is it just one head that needs to be swapped since the later engine has 2 CMPS vs only one on the early one....????

Has anyone done this exact change?

 

There is a flow difference in the heads for the two engines, and the valve sizes are different- I would swap both heads for that and other reasons (brand new head gaskets etc.) You need to swap the flex plate as well. Recommend swapping the oil pump and sump as well, they were upgraded on the AJ27.

I *think* that is all you will need to change- I swapped an AJ26 N/A into an AJ27 N/A so it does work. Let me know if you want my to swing by and point out the differences, I should be in LA at sojme point this week. Feel free to PM me as well.

 

The valve diameters of the AJ 26 and AJ 27 are the same. The intake port divider is re profiled to help reduce wall wetting from the more efficient air shrouded injection system fitted to the AJ 27. If you look at the port divider on the aj26 its almost the full length of the port.

Lots of very good threads covering swapping both ways or from aj26/27 to 4.2.

https://www.jaguarforums.com/forum/j...k-4-2-a-23763/

https://www.jaguarforums.com/forum/x...-thread-61113/

 

Sorry, that is correct- they are the same diameter, but the stems are different lengths.

I would swap the heads.