I think that is a manufactured notch in the guide, if I recall correctly. Have a look at the photo of the front of the engine I posted to you earlier. If you zoom up, you should have a good view of the guide sets. I am not sure why they are built like that, but I think that is what you are looking at. I strongly suspect the ticking is from valve noise, brought on by chains with no tension.

Hope your back is better soon

Thanks for the well wishes,....seems a bit better this morning...still real weak...BUT.......I like your explanation of noise source, seems like that was a hot topic when I first started visiting a jaguar forum (Roadfly) seeking advice and information http://forums.roadfly.com/forums/jag...9478021-1.html As always, thanks for all of your thoughts and suggestions!