Changing out the plugs this weekend, I want to be sure to replace with the correct plugs. I don't know if the plugs in the car now are indeed the correct plugs, Champion RC9YC. Please advise.

 

Refer to JTIS or the Workshop Manual for correct plugs. If you have the Owner's Manual, check for the spark plug listing.

You can also use the search function on this forum for more information as this subject has been discussed quite often.

 

Hi R-Rocks,

The Champion RC9YC is the plug you want. You will also find it listed as the 344 under Champion's newer numbering system. I and many other owners have tried more expensive platinum and iridium plugs with no discernible improvement in performance and occasional problems that have gone away when the owner has gone back to the RC9YC. They're cheap and un-glamorous but they're the plug the Jaguar engineers used when designing the AJ6 engine. They get the job done and in more than 20 years of Jaguar ownership I've never heard of a problem associated with a Champion plug unless it had been used far beyond its reasonable life expectancy.

They're available almost everywhere and Rock Auto has them for $1.31 each.

Do follow the gap and torque specs when you install the new plugs. Neither under- nor over-tightening is good.

Off the top of my head, I think the correct gap is 0.035 in. / 0.9 mm, but please double check.

Cheers,

Don

 

Thank you Don.