Spark Plugs

Alec,

One other thought. While you're in there, check the fuel rail and injector hoses very carefully. The V-12 engine generates a huge amount of heat, which destroys all of the rubber components over time, including the injector hoses. Fuel rail leaks will lead to an engine fire. While you are in there, now's the time to check them carefully and if there is any question that they might be leaking even the slightest, consider changing them. And always carry a fire extinguisher behind the driver's seat so you can grab it quickly if you need it (I'm not kidding).

Steve Weinstein, JTC-NJ
'72 E-type 2+2
'70 XKE FHC
Former '89 XJS owner

Alec,

I've said this before many times, here and elsewhere, but if you are working on an XJS yourself (or even if you're paying someone to do it for you), go to www.jag-lovers.org and download "The Book" by Kirby Palm. I contains the collected wisdom of XJS owners from all over the world and is invaluable.

As far as a tune-up goes, a few thoughts:

You can't really work in the "V" without removing the cruise control unit. Just do it. I took mine out and never put it back, because it didn't work anyway. It's just in the way, it's garbage and it opens up the top of the engine a lot.

Be patient. With all the "stuff" in the V, it is a royal pain to get the wires off and the plugs out and back in. Having a long ratchet extension and a universal adapter helps a lot. Also, having a spark plug wand (stick with a rubber boot for putting the plugs back in) helps a lot too. Be sure to put anti-seize compound on the threads and only tighten them hand tight.

Watch the gap on the plugs. The Lucas ignition system wants a .025 gap. Don't open it up to .030 or .035 to get a "hotter" spark. Make sure all the plugs are gapped to .025.

While you are changing the plugs, that's a good time to change the cap, rotor and wires. Buy an OEM cap and rotor. Don't buy a cheap aftermarket replacement. You'll be sorry. And be sure that the cap is the vented cap, and be sure that the vacuum line to the vent is connected properly at both ends. Fumes build up in the distributor from the crankcase and they are known to explode if not properly vented. Consider going to Magnecor wires (I have a set for an XJS that I'd sell you, new, unused, that I don't need since I sold my '89 last year).

I put NGK V-groove plugs in my '89 and liked them a lot. I did not get the Platinum plugs, however. The regular NGK V-grooves worked just fine.

BTW, changing the 1A and 1B plugs is impossible without moving the AC compressor. Just loosen the AC belt, unbolt the compressor and push it to one side, change the plug, then the other. You don't need to evacuate the system, just be very careful moving the compressor to the side. There is a special tool to change those plugs, but after an hour of trying to use it, I gave up and moved the compressor. Easiest way to do it.

Also, if you pull all the wires out, replace the cap and put them back, be very careful to get the right wires to the right plugs. And while you have the cap off, it's a good time to check that the advance is working properly and to lubricate it. Check The Book and the ROM for information on how to do that.

Hope that helps.

Regards,
Steve Weinstein, JTC-NJ
'72 E-type 2+2
'70 XKE FHC
Former '89 XJS owner

I was also wondering where I could go about finding a place to get some nice NGK V-GROOVE Platinum spark plugs for the XJS. Also I dont know what kind of core rotor and cap I should go with if it should just be the basic stuff that they sell out of Terry's Jag or something else?
Alec