My ’94 V-12 XJS has the Marelli Ignition System with the infamous cap and rotor. It’s not news to anyone that good OE parts for this are getting harder and harder to find, and the reputation of the aftermarket parts are terrible. So what’s there to do after the sealant has been added to the rotor and the post trimmed back? Wait for the cap to start showing some signs of real aging, then buy and modify a cheap replacement?
I’ve spent a bit of time at other forums lately looking for an answer. What I’ve seen recommended a few times is to swap out the Marelli distributor for a Lucas and adding an MSD Automatic Coil Selector into the mix (also see page 164 in “The Book”).
What I’m wondering is; Has anybody here done this? If so, (lots of questions) difficulty, tricks, pitfalls, results, etc...
And for those who haven’t tried it, or don’t need to. Any opinions?
Fire away!

 

sucks that marelli is supposed to be an upgrade.

 

I have the old Lucas style in my 83, and it works fine. But to change from your system to a Lucas, wouldn't you have to change the ECU as well?

To be honest, if I were to change my system to something else, I'd put a crank sensor on it and go with a distributorless ignition!

 

Now that I know how to do the Marelli sealant mod, I'm happy to stick with that till it's time to lose the distributor altogether.

 

No.

The modification being considered isn't really a conversion from Marelli to Lucas ignition systems. It's a matter of using the Marelli ignition system with a Lucas distributor.




It has a crank sensor and some guys *have* gone to a DIS.

Cheers
DD

 

Which might be never :-)

Cheers
DD

 

The bona-fide Marelli cap is discontinued. As of a couple years ago, though, the real Marelli rotor was still available from Jaguar.

I've heard that the true Marelli cap will last almost forever with just cleaning the terminals every so often. If that's true, and if you pick up a spare Marelli rotor or two while you can, you'll be good to go for many years

Quote:

and the reputation of the aftermarket parts are terrible.

If you have an aftermarket cap in one hand and the true Marelli cap in the other, you'll see and feel the difference immediately.

FWIW, though, I installed an aftermarket cap on an XJS a couple years ago and all's well, so.....?

Remember too that old, high resistance plug wires and worn, incorrectly gapped plugs are part of the problem

Quote:

So what’s there to do after the sealant has been added to the rotor and the post trimmed back? Wait for the cap to start showing some signs of real aging, then buy and modify a cheap replacement?

Never done it but was tempted on a friend's XJS. In the end he decided to nurse the original system along.

The conversion makes good sense, though, as it obviously puts the issue to bed entirely.

OTOH, and to be perfectly realistic, I suspect the reason so few have done the conversion is because the failure scenarios of the Marelli system are well known and easily avoided. The system will perform beautifully for ages IF routine servicing is kept up (new plugs and wires every few years) and the sealant trick is used. Just to play it safe pop the cap off once a year to inspect the rotor...or maybe every 2-3 years if the car is driven only on weekends.

Cheers
DD

 

Yeah, the pros and cons.
Even in recent posts, Mr. Kirby recommends the swap and getting rid of the problem for good. No more worries about flameouts.
On the other hand. Why fix something that ain't broken? Especially since I am a novice at this (last distributor I touched was on my 1976 260cc 5 Speed Cutlass)(it was a pretty new car), and I want to work on this car myself.
I think I'll stick with what I've got, it is just a weekend ride and I can find a low mileage Italian cap.
I am curious about the DIS. In the future, that may be an option. But, I'm under no illusions that this is an easy thing. What's it take to do that?
Thanks folks.

 

I have had no problems with mine just keep the maintenance up you will be fine, most of the problems with XJS's are due to a lack of maintenance from previous owners.

DIS is a good mod, the later 6L V12's came with a version of Fords EDIS, this mod has been done a few times on older V12's using MegaSquirt or you could use MegaJolt for ignition only.

 

I have a 94 V12 and I just changed out the cap and rotor... Silicone squirt and all that. She runs fine in the sense that the cap and rotor are no longer a problem.

 

I had a 74 v12 e type and replaced the lucas with a Crane ignition. Worked great.