For a 1999 XjR will any other year heads work on the 1999 4.0 engine?
Thanks..

 

I believe the 1999 thru 2003 heads will be compatible.

 

The North American 1999MY XJR is AJ26.
Although the normally aspirated 1999 XJ8 is AJ27, the intake cams ARE DIFFERENT.
The reluctor lobes for the CMPS are different between AJ26 and AJ27.

Also, the VVT is only on the Normally Aspirated version.(the oil gallery needs to be 'plugged' if a VVT head is used)

Any 4.0 V8 cylinder head casting will work if you swap parts to make a compatible setup.
Jaguar addressed this issue with a TSB many years ago.

 

Understood. Thank you for the replies!
RJ

 

ALL 4.0 engines can be swapped/parted/integrated if you know the correct designation you are after.

I traded work for a 2000 XJ8 car with a 'bad/seized' engine. (good gearbox and body)

I had another customer bring me a 2000 S-Type 4.0 with an engine that had a 'dropped valve seat'. The customer bought a 2001 wrecked complete car for the engine.

I replaced the 2000MY AJ28 'bad head' engine (slightly dented piston) with the good 2001 engine and the customer left me the 'bad engine'.
The S-Type was a very happy car.

I used the AJ28 block with an AJ27 sump and some heads I had from a bad AJ27 'nikasil-block' for my 2000 XJ8 that my wife drives every day.
The XJ8 is a very happy car.

You can 'mix-and-match' all sorts of combinations as long as you understand the differences.
Read my Jaguar engine training course 168 I had converted from paper 3 ring binder to .pdf years ago.

 

Sometimes I envy Bob, having all the various parts and Jags
he has at his disposal. I would need a lot more space though.

 

He's the American version on my Dad god bless him, the only difference is my old man's Jaguar knowledge covered the 60's range, "They were rusty in the showroom Sean!"

I asked this same cylinder head question on here over 14 years ago - guess who gave me the info?

 

I have 14 acres but only about a half acre is dedicated to my 'salvage yard/shop' area.(gotta have room the the house and livestock)

 

And...I am certain Bob does Not want to hear any "Bob Ross" comparisons
with his "happy little S Type" and his "Happy little XJ8*

 

I like happy cars. (I can't draw and I can't paint, although I did paint one of my tractors 'Ford blue')

 

I remembered another document we got at the dealer regarding cylinder heads on the V8.
Tech Tip from a few decades ago.