I read the thread in the sticky called "4.0 to 4.2 swap success", but it dealt primarily with supercharged engines.

I have a 2000 XK8 coupe with AJ27 4.0 engine. The timing makes noise on startup. Additionally, the car makes a little bit of blue smoke on startup, which goes away shortly. I suspect worn valve guides and seals, but not 100% certain as to the root cause. The engine has 144K on it. I can get a 2006 4.2 engine for reasonable money. Have you done this swap?

Ideally I would prefer to keep the 4.2 complete long block (block and heads) and reuse the front cover and ancillaries from a 4.0. My question is, has anybody here done it? Any pitfalls I should watch out for? Is the VVT mechanical hardware the same on AJ27 and 4.2? Will the 4.0 intake manifold bolt on to 4.2?

My backup plan would be to use the 4.0 heads on the 4.2 engine, but since I suspect that my heads are worn, I would have to rebuild them. I would prefer to use the 4.2 heads with 4.2 block if possible.

 

Member smoggyx100 has done this, albeit the donor was a 2005 S-Type:
https://www.jaguarforums.com/forum/x...5/#post1772265