I am trying to do the 4.0 to 4.2 motor swap in my 2001 XKR. I have read the post on this issue several times, but can not figure out how to get around the vvt in the newer motor. The post said to use the cams from the 4.0 motor if the new motor has vvt, but it not address what to do with the vvt. Someone said to use an external controller to handle the vvt solenoids, but that is a complete mystery, as I have no idea where these solenoids are or where to get an external controller.. The motor I am replacing is an AJ27s and the new block is from a 2008 XKR. Any help on this would be of great help. This is my third Jag, so I now own a 2004 XJ8, a 2003 XK8, and a 2001 XKR. AM i crazy or what. thanks guys. steve in cape coral, fl.

 

I would sell the VVT units, or safe them for just in case you ever want to give it a go.

For now re-use your AJ27 cams (and gear), assuming your old engine still has the older style chains (so not the morse chain on the 4.2 one), you also have to swap the chains/guides, or get yourself a morse chain gear.

 

I thought that the XK8 had VVT, but the XKR did not? Did I miss something?

 

Thank you Avos and the Lonestranger for the response. The New block will be here in a few days and I will know more about what I am up against. I will pull the old motor out in two days. Still have not figured out what was wrong with it yet. Did a leak down test on a couple of cylinders and nether would hold air. Also noticed the motor was very hard to turn even with no plugs or belts. Doesn't matter, just curious. I am sure I will need more help later, so thanks again for the info. steve

 

External controller for the VVT has been done.

https://www.jaguarforums.com/forum/s...23/#post566543

With a 4.2 you have a robust engine, why open it up if you don't have to?

 

OK guys, I got the newer motor today and started looking it over. It is a vvt setup. So on first glance I see that the new blower pulley is a harmonic balancer and the 4.0 is not. Will that upset the crank if I replace the pulley with the smaller one? The next thing is the exhaust manifold is different and will have to be changed, so with that in mind along with making the intake manifold fit, and changing out the cams, wouldn't it be easier just to swap heads? Which brings me to another question. Has anybody reused the head bolts with success? The cheapest I have found them is $160 a set. I know these questions are the first of many things to overcome. Please keep in mind I am not looking to beef up hp, but to build a decent running car without going broke. thanks steve