Hi all, this is my first big job on a vehicle, so my apologies if this seems ill-informed (though I have a great and knowledgeable person helping me through the process who has worked on these cars for over a decade). The car I’m working on as a Jaguar XJ8 base model from 2000 (4.0 V8). I’m working on putting the car back together after doing a head gasket job and for whatever reason I’ve now been through two VVT bush carriers because they keep cracking on the driver side. The engine is set to top dead center as well as the cams, and the engine is timed properly. The passenger side went in fine with no issues, but my drivers side VVT bush carrier cracks where the screw protrudes above the tensioner (farthest screw towards the middle) where a nut is attached as opposed to a bolt in the well. Theres a small gap (circled in the picture) that I can’t seem to close without cracking this part of the piece. When all the other screws are flush, it’s still there, but looks to be seated flat in the cam sprocket and looks identical to how the passenger side is. Am I missing a second spacer? Or is there a way to advance/retard the VVT unit inside the plate so it sits better in the well? Either way, I’d like to say 3rd times the charm once this last one arrives and get this thing running! Let me know if you need any additional information.

 

That MORSE STYLE primary chain is NOT original to the 2000MY AJ27 engine!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

I don't know what 'hybrid' engine you are trying to build.

SOMETHING IS NOT RIGHT!

PS The engine does NOT TIME at TDC!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! !!!!!!!!!!

 

The chain was the one originally on it when I bought it. I had attempted to reuse the new one that came with the timing kit, but they didn't fit on the sprocket, so I reused the main chains as there were no problems with them (they were replaced 20k miles ago). As for timing, I followed the directions right out of the JTIS manual (that was confirmed by a Jag mechanic) by setting the timing with the tool inserted into the sensor hole on the underside of the car, and locked the cams in place before removing anything. Everything went back where it was taken off, and the chains are correctly placed in the same spots they were removed from (also confirmed by a mechanic). My only issue is the one spot where the VVT bush carrier seems to bend when torqued to spec - I believe my engine is an AJ26 not the AJ27 if that helps at all. Either way, I believe the parts are the same for both engines, just need some help with that

 

Of course the Bush Carrier, while held firm by its two mounting bolts, will crack if forced to close the gap on the stud you have shown. Also, the spacer pointed at by the yellow line on the picture below is not shown on the parts diagram so I don't think it should be there. It seems that the spacer was inserted to keep the stud further out (not threaded fully into the head), otherwise it would be too short for the Bush Carrier to be attached to it. When this stud is tightened over the inserted spacer, it may not allow the chain tensioner to freely swivel as required to apply pressure on the chain (unless there is another spacer between the stud and the cylinder head).

I have not worked on VVT-s as my engine is SC but the mismatch you are having between the stud and the Bush Carrier could be due to incorrect carrier for the cylinder head you have. The AJ26 carrier is NCA2617CC and AJ27 is AJ8 1263.



If you cannot find a Bush Carrier that would match, you may be able to solve the issue if you machine a stud with its portion above the hex extended. The Jaguar Parts Catalogue shows only one part number for the stud, NCA2028BA. It looks like this:


You seem to have somewhat different stud.

 

I will try this - thanks so much for the tip! My bet is it's the wrong stud, and the new one you have suggested is the correct piece. I will update in a couple days to see if this fixes the issue.

 

When you reinstalled the carrier assembly, did you push it all the way into the VVT first? Just a thought.

 

So I found the issue. The VVTs are not seated all the way in the well because they are not spun correctly - the bolt/stud, while not the original parts listed above, function as intended and should be fine for continued use (confirmed by seasoned Jag mechanic). The only thing is I’m not sure how to spin the VVT to line up correctly, or if I need to spin the camshaft (which I’m assuming is wrong but maybe not). If I spin the plate around a 16th of a turn clockwise on both sides, they sit correctly in the well. However, the bolt holes to bolt it down don’t line up. Does anyone know how to line these up so the VVTs sit correctly in the right orientation to screw them down?

 

By your "spin the plate", do you mean rotate the chain sprocket of the CVVT unit after tremoving the allen head bolts on the chain sprocket?

Did you remove the marked bolts:

 

I did not. Is that how you rotate it?

 

No, you should not touch those allen bolts. The CVVT unit will fully seat on the camshaft in any orientation (rotation wise) so you need to explain better what you mean by:
"The VVTs are not seated all the way in the well because they are not spun correctly..." and "If I spin the plate around a 16th of a turn clockwise on both sides, they sit correctly in the well. However, the bolt holes to bolt it down don’t line up."

I have attached a PDF file showing the method of installation of the VVT and the exhaust cam sprocket and their correct timing. Take note that the centre bolt holding the CVVT to the camshaft is torqued to 85-90 Nm (not to 115-125 which is for VVT).