www.jec.org.uk

What is the mod for the Marelli cap? Something about silicone sealant or something?

the theory goes...

under the rotor arm the central shaft is close enough to cause and arc when the spark plugs and or leads have a high enough resistance to make the spark find ground another way

one way to eliminate this ( other than a properly serviced engine ) is to remove a small amount of metal to the top of the rotor shaft while retaining its locating capabilities, and then when the rotor arm is placed on to add a little silicone sealant to the top of the shaft to aid insulation

personally , i have not bothered, as i have all new components of genuine Jaguar/Marelli production , no aftermarket caps, plugs or leads , cost a fortune, but worth it to me


BB

Also follow the link below to find how to download Kirby Palm's xjs book, I'm sure the subject is covered in depth somewhere there .

http://www.jec.org.uk/registers/xjs/running.php

OK, thanks guys.

Cor Blimy BB, that's a bit drastic, machining some metal off the end of the rotor drive shaft !

As you say, Got to be better to service the system correctly

personally , i have not bothered, as i have all new components of genuine Jaguar/Marelli production , no aftermarket caps, plugs or leads , cost a fortune, but worth it to me


BB

I realise this is over a year old, but wondered where you were able to buy genuine Marelli rotor arm and distributor cap from ?
Are they still available ?

I'm not sure if these are genuine or not.
https://www.britishparts.co.uk/products ... rm-JLM1911
This one says it is genuine.
http://www.ebay.co.uk/itm/JAGUAR-XJ12-X ... xy63FS2Q4I

http://www.ebay.co.uk/itm/Jaguar-XJ-Sov ... SwU-pXq1Go

Paul,

If you just check the Jaguar website, you'll see that JLM1911, the rotor arm, is still available from Jaguar, about £11 with the JEC discount that your dealer will give you.

Paul

as above

the rotor arm is readily available from jaguar, as is the distributor cap i think , but is expensive ( relatively )

but

be weary of internet or ebay sales that say they are selling a Marelli cap for the V12 , what turns up on your doorstep will undoubtedly not be the genuine item

personally , you are much better off using genuine Marelli items , as the materials used in ' lesser ' brands are not as robust ,

BB

If push comes to shove, I have a brand new genuine marelli dizzy cap , I also have some perfectly good previously used genuine marelli dizzy caps , these are personal stock for my own cars,

so give me a shout if your stuck and we can work something out

BB

The Marelli cap has been NLA for ages, and as BB said: virtually all of the online sellers offer aftermarket rather than the real deal.

Look closely and you will see that many sellers say something like 'Marelli style' in their small print...

I've purchased several aftermarket caps, and they're OK, but definitely poorer quality than original. When doing your distributor cap/rotor, also get a new distributor gasket/air filter. Both are still available new for very acceptable prices.

Thanks to all for your replies.
Last time I replaced the cap and rotor (18months ago) I obtained Marelli rotor arm but the cap (supplied by British parts) was manufactured by Intermotor.

How frequently in terms of mileage would you recommend replacement?