Doing some basic items on my Jag and found the NGK iridium's to be a popular plug. I thought all x308 xjrs had the same engine but it seems 98 has a different engine code and calls for a .50 plug gap... As I recall you do not want to gap the iridiums.. Anyone know how they come? BKR6IX IIRC. Thanks in advance

 

Found the gap on ngk as .044'' Im pretty comfortable running it as is unless there are any other suggestions. Thanks in advance

 

Check the Threads with spark plug gap...loads of info.

 

I put these in mine, left the gap at .044 IIRC. Work great.
BKR6EIX-11 iridium
Rock Auto, $51.76

 

Great, just what I was looking for. Sometimes researching previous threads will make your head spin. Most have different model engines. .35 seems too small and .50 too big.

 

NGK is the OEM plug fitted at the factory.
Yours being a '98 will have the AJ26 engine. 11/'97 - 02/'00

The later AJ30 engine ran from 02/'00 - 02/'02

Yours is fitted with PFR5G-11E standard plugs with the Iridium
equivelant being BKR5EIX-11.
Under normal driving the 1.1mm 44thou. gap will be sufficient
but under hard driving conditions, the engine responds better with
the 1.3mm 52thou. gap.
You can safely adjust the gap at the outer electrode with a proper adjusting tool.

Now, if you really want to go the whole hog, you will 'index' your plugs ;o))

 

What would be your suggestion? Its a little confusing as on rockauto.com they are bringing up #6 heat range plugs. You think iridium is overkill?

 

X308XJR
I looked up your 1998 XJR on NGK website and the NGK 3764 BKR6EIX-11 iridium is recommended:

NGK 3764 BKR6EIX-11 Iridium Spark Plug

Also on the webpage - click on specs tab and you will find the Plug Specs says:

Gap: .044" (1.1mm) - pre-gapped
Heat Range: 6 - for this spark plug

Advance Auto Parts are selling this spark plug for $7.09 each = $56.72 for 8 plugs, but they have an active coupon code TRT30 which is a 30% discount and free pickup at local store (same day ordered online). Your total cost will be $39.70 plus sales tax.

http://shop.advanceautoparts.com/p/n...ark+plug+ngk+3

I installed this same spark plug in our 2001 XJ8 in March 2011 some 30,000 miles ago, engine still running strong.

See my post# 13 in the following thread:

https://www.jaguarforums.com/forum/x...k-plugs-45749/

Jim Lombardi

 

Jimlombardi's post regards heat range is most likely correct for the US market.
I gained the info from our Australian NGK site....we run a better class of fuel ;o]
Iridiums are definately the way to go on any of the AJ V8 engines....wouldn't waste money on any thing else.

 

As a counterpoint, in my mind NGK/Denso platinum plugs are fine if one is into changing plugs more frequently. And why not? The plats are cheap and frequent changes reduces the risk of a seized plug stripping the threads.

 

Hi
I found on my car NGK IFR5N10. After a quick search on the NGK site i decide to order 8 new spark plug NGK 7092 BKR6EGP Single Platinum.

I will receive them at the end of May. When i will replace the secondary tensioner i will change also the spark plugs.

Autodata and NGK says that NGK 2341 PFR6G-13E Double Platinum Spark Plug are the OEM spark plug for 2000 XJR.
I will come with the result after the installation.

 

Ok, I'm gonna go with the 6 heat range iridiums at .044 and give them a try, if that 30% discount still works that's a steal. I use 93 octane and occasionally give it a thorough beating.

I remember when I turbo'd my jetta years back you would shorten the gap not enlarge it to prevent spark blowout. Even though .08" isn't much bigger I'm curious why some go for the .052...

I'm sure I could start another thread on this but what was Jaguar thinking not putting a limited slip on their performance model

 

Here is an article on NGK US website about not using anti-seize lubricant on NGK sparkplugs -

The use of anti-seize compounds on spark plug threads that have a metal shellplating (i.e. Zinc or Nickel plating).

http://www.ngksparkplugs.com/pdf/tb-...1antisieze.pdf

Quote: All NGK Spark Plugs are manufactured with a special trivalent Zinc-chromate shell plating that is designed to prevent both corrosion and seizure to the cylinder head; Thus eliminating the need for any thread compounds or lubricants.

Also (another quote) Applying anti-seize to the threads of spark plugs that have a metal plating allows the installer to mistakenly over-tighten the spark plug in the cylinder head; This stretches and fatigues the threads of the spark plugs, causing a much higher probability that the plug will break during installation or in some cases upon removal.

I thought this might spark some interest and plug any use of the anti-seize lub on the NGK spark plug threads.

Jim Lombardi

 

Just to answer your query regards plug gap.
Back in 1998 Jaguar was having a few customer complaints about lumpy idling on the AJ26 NA engine.
The normal plug gap was the 0.44" and a TSB was put out to increase the gap to 0.52" to cure the lumpy idle.
Mine being a mid year '98 AJ26 4.0 litre NA engine, I have always run the 0.52" gap with no problems in the last eight years of ownership and over 200,000klm.
I also use a SMALL dab of nickel anti seize on the lower 180 deg. of the plug thread and tighten them to 18 ft/lbs with no dramas....NO plug thread stretch or, cyl. head plug thread damage.
I think with all these things, they are blown all out of proportion and the knee jerk reaction sets in.
A little common sense and mechanical sympathy goes a long way ;o]

 

The oft quoted NGK US bit about anti-seize is only found on the US site. Not the other national sites or the parent site.

My suspicion is that the US bit is due to too many ham fisted amateurs.

Ford started out with a no lube recommendation and have now gone to recommending anti-seize on plugs in their aluminum headed engines. They were paying for too many stripped out thread repairs including complete head replacements.

Jaguar has always recommended anti-seize in the service manual.

NGK build plugs ... Jaguar knows their own particular engines.

As do Ford and BMW.

I use engine oil.

My plugs don't creak when coming out ... I don't break out in a sweat dreading stripped spark plug hole threads.

 

I was bored today and pulled a plug, it had a small amount of oil around the plug. It was an Autolite double platinum 3923 gapped at .047 it seemed. I may leave them since these have been changed since factory. What do y'all think of this plug? They had very little torque on them.