Marelli Caps & Rotors

In preparation for the arrival of my new 5.3 '92 coupe, I have been reading once again Kirby’s magnificent book, as well as the Nine Lives C.D. (the latter now 16 years old, btw). :books: I noticed a passage in one of these sources stating something along the lines that “Marelli caps and rotors are no longer available/made”. wth? :open_mouth: And this, after reading how important it is in those books to use ONLY Marelli for these fire-prone parts. Please tell me it isn’t so! If so, what should we use in place of that brand? :confused:

Atty, several of the usual parts houses we discuss on this forum such as SNG or XJs have their version of the distributor cap for Marelli. And rotor. And don’t forget the gasket for the cap.
If the Marelli ain’t available…

Thanks, Jim. After checking some of the usual suspects’ websites, although they seem to keep the brand name close to the vest, I think I have figured out pretty much what they are selling in place of the real thing is a cap made by FACET. :triumph: Does that sound right? Only problem now is that apparently FACET doesn’t make a rotor. So, which aftermarket rotor(s) are acceptable? I saw one by Beck-Arnley, whom I have trusted before for other parts for my Jags w/o fail. There is also one made by “NTK”, but don’t know how good/safe that one is. :grimacing:

btw, I never understood why Jag switched from one brand to another one in regard to the caps and rotors … it was like going from the frying pan into the fire (no pun intended) … I thought the whole reason they switched away from Lucas was b/c of the unreliability of the “prince of darkness” … They end up switching to something that is generally more reliable, but causes ENGINE FIRES when they do go bad … :fire: wth?

I think SNG had the cap, rotor and gasket. I have had good success with them.

About 8 to 10 tears ago I did replace mine and ordered from Welsh. It was a Marelli brand.

There are many that offer Marelli brand, but NONE that offers the actual Marelli cap anymore. This is the unobtanium cap (notice the brass terminals):


while this the the Marelli-style (notice the aluminum terminals)

Pictures shamelessly lifted off “The Book”

Hey Steve. Good point.

But my point was that you can only get what is now available. Which is becoming harder and harder to find for V12 XJSs

Absolutely true Jim. Finding quality parts these days is getting harder and harder. The global industry and the repackaging business – one never knows what’s what anymore.
And for the record – the Book talks a bit about the price of the Marelli cap (the real deal, NLA anywhere in year 2019), but the Lucas caps (all aftermarket) and the current Marreli-style caps are not very different price-wise. Mine for example came in an “Intermotor” box cost was less than $90 shipped.

Are we in the transition period, where Jag stopped making parts about 10 years ago, and the global aftermarket choices are dwindling as demand goes down because less and less XJS V12’s are on the road. But once these cars are collectible, the specialized aftermarket goes up?

Doesn’t the E-Type have a big aftermarket for parts now?

This might be true in general, but Jaguar never made any distributor caps. The genuine Marelli cap which was mentioned earlier was/is a high-$ item because the exotic Italian cars with v12s also use the same ignition system.

My point was that there is no shortage of aftermarket parts for the XJS, however, the quality of many of those is arguably questionable. This is why I keep spare ignition components in the trunk, just in case…

I just looked at
They are showing genuine Marelli cap. Might be worth it for AttyDallas calling them to verify

Thanks for the lead, Jim :smile: Yes, I wondered why it seems more and more caps and rotors are going with aluminum contacts vs. copper. Although aluminum is not quite as good a conductor of electricity as copper, the latter is the cheaper of the two metals these days. I guess then it’s just a matter of “cost cutting” ? :confused:

Good idea! I might need to copy that. So far all I keep is spare relay.

:slight_smile: I have the original cap, rotor and one of each – amplifier and coil – tucked in a small box behind the CD-changer. Some will call it OCD.

By the way Jim, the link to the vendor you provided last night – it says “genuine Jaguar” and the retail price is just over $200.
This is NOT the real-deal Marelli cap. It will be, and I am 100% sure, the same cap everyone else sells, but will come in a nice and shiny Jaguar box. Don’t ask me how I know.

To recap, dizzy caps that do NOT have MAGNETI MARELLI embossed on the top and no brass terminals, and only say “Made in Italy” are aftermarket reproductions. $100 or less all day.

The NLA, real-deal Marelli cap, if you can find somewhere NOS, will probably deplete your wallet of at least 400-500 Benjamin’s. That is, of course, in the event some Lambo-owner does not outbid you.

Several years ago when I started the restoration of the engine bay in my wife’s 1990 XJ-S convertible (5.3L with Marelli ignition) I was shopping around for parts and ordered what I thought was an OEM Marelli distributor cap through the local dealer by the Jaguar part number JLM1909. When I went to the dealership parts department to pick up my parts and opened the box with the Jaguar decal showing “JLM1909” I found the much lighter cap with the aluminum terminals and “Made in Italy” cast into the plastic. I had my much heavier OEM cap with “Marelli” cast in the plastic to show the parts guys what I was looking for. They told me that the original Marelli caps were no longer available and the part with the aluminum terminals was what they were using and selling. I declined the part and was fortunate to find a NOS authentic Marelli cap and rotor which I installed.
The reason that I did not accept the “Made in Italy” cap was I experienced a failure in 2005 or so with one of those caps. I drove the car one evening shortly after replacing the cap, rotor, plugs, coils, and wires and it started to run a little rough as I approached my home. I pulled the car into the garage, and when I opened up the hood I was rewarded with a light show of sparks shooting out of the top of the cap. I shut down the engine, removed the cap, and found the plastic had melted on one of the coil posts. Luckily I kept the used Marelli cap and rotor that I removed and installed them temporarily until I found a OEM Marelli cap and rotor to install. I got a refund from the supplier (Coventry West) for the failed cap and they told me that they were going to send the failed cap to their supplier after the received it from me.
I have not read of any recent failures of the “Made in Italy” distributor caps on this list so maybe they are OK now?


There are – or were at one time – differences, though. If you turn the cap over and look at the spring-loaded carbon brush in the center, the carbon brush should be surrounded by a sleeve of metal. Some early aftermarket caps just had that carbon brush sliding in an opening in the plastic, with the electrical contact made at the bottom of the hole. These are unacceptable, period. Make very sure you get a cap with the metal sleeve surrounding the carbon brush.

If you’re stuck with a sleeveless cap, I did succeed in modifying one. Basically I drilled out the hole to a 1/16" larger diameter and fit a piece of brass tubing (available at hobby shops) in the opening, secured with a bit of JB Weld. The ID of the brass tubing is the same as the original hole, so the carbon brush and spring slip right back in place when done. You want to make very sure that the brass tubing makes electrical contact with the aluminum terminal at the bottom of the hole; I formed a “tang” of sorts on the bottom end of the tubing to firmly jam into the aluminum.

It has also been suggested that the screws used to hold the Marelli cap to the distributor should be removed and replaced with plastic screws. That’s because there have been cases where the sparks break through the side of the cap to the head of a screw.

Remember that the routing of the plug leads is important. Jaguar issued a TSB to provide a little plastic clip that – IIRC – clipped the 1A and 1B leads together on top of the A/C compressor. I think the point is to keep them away from the injectors; a lead laying up against an injector coil eventually damages the coil, causing a fuel leak and a fire.

Sorry to go slightly off topic, but I had a similar issue with Lucas caps & rotors. There appears to be blue aftermarkets, and black aftermarkets that say “LUCAS” on them. They both have aluminum posts.

I bought the black LUCAS imprinted one because it seems to be higher quality? Along with the black rotor. So far so good, 9 months later.

oh, and I bought some coolant gasket material for $8 and cut out my own cap gasket. MUCH cheaper than buying flimsy $20+ gasket!

Kirby (or anyone else) … I saw a topic about this issue mentioned in either the Book or 9 Lives … it had something to do with substituting (modifying?) a Lucas cap & rotor so that it would work in a Marelli car. I didn’t read the article though :blush: Is that really possible (and advisable)?

I think you’re right about the transition period for an old car, with a lack of replacement parts, to a classic car with a good supply of remanufactured parts. My 1968 Alfa has nearly enough aftermarket support to build a complete car. The 1992 SAAB 900 is now moving into the window. I’ve seen a few cases with the availability of pre-facelift vs facelift parts. I’ve been trying to track down a rear bumper beam, they’re being remanufactured for pre-facelift but not (yet?) for anything after 1991.

But I see problems head for newer classics. It will become cost effective to produce small runs of remanufactured parts like body repair panels, lighting, etc but I don’t see that happening with the complex ECUs and control systems that are now embedded into cars since the late 1980s. I’m trying to find a good ABS ECU for the SAAB but can only pick from unknown S/H stock.

In theory, yes. An MSD Automatic Coil Selector was used to connect the two Marelli coils to the single center post on the Lucas cap. Problem is, it turns out the MSD Automatic Coil Selector is a POS that burns out within seconds.

You might be able to make it work by creating your own diode pack. What is needed is a diode between each coil and the center post on the cap. The two diodes need to be rated for something like 50KV each, which is apparently unobtainium, but it might be possible to chain several diodes in series to add up to a 50KV rating. They’d all have to be encased in a length of vinyl tubing or something. But no, as far as I know no one has actually tried that.

Several have taken the more extreme measure and simply replaced the entire Marelli ignition system with a Lucas CEI system.

Reminds me again of my '72 Opel GT I owned back in the late '80s … Getting needed new parts back then (out of GM) was like pulling teeth … Now, 30+ years later, since they are a collector’s “classic”, new and refurbed parts for them seem to be everywhere on the Internet. In fact, there is a co. out in N. CA that sells nothing but new and refurbed parts for Opels, and does a good business … so much so it’s even worth it for them to invest a few $$ to import some of the parts from the Opel co. in Germany and even have a few of the parts brought back (i.e. retooled up). :moneybag: Wish they were around back when I owned mine!