Sorry for bringing this topic back up. I've seen through out the forums what the gaps been. Ranging from (.032 -.039) (.052 - .053). And what plugs. I changed the plugs to Autolite last winter. And they're just horrible. I am changing them to NGK (3764) BKR6EIX-11 Iridium IX Spark Plug. On my XJ8 2001 (build date 11/00) Just wanna know the gap and are these good plus?

 

If they're the OE plugs they'll be fine. (Why use anything else...)

 

01 probably needs the smaller gap, there's a table in the forums somewhere that lists gap based on model and vin ranges

 

Jaguar issued a TSB almost 20 years ago to address the plug gap.
The gap recommendation was revised (1.3mm) to improve engine idling quality.

I don't know of any later revisions for the 4.0 engines.

bob

 

Here's the table I was thinking of, post 17 https://www.jaguarforums.com/forum/x...7/#post1598315