The Jaguar XJ6 “Lucas Constant Energy Ignition System” (CEI) has many English Car Forum Posts on the design theory, purpose, effectiveness vs. other ignition systems, detail parts and repair. Andy Blackley provided the initial discussion on various Jaguar Distributors and Excel Spreadsheet plots of the Distributors Advanced Curves for various Jaguars models.
Given the Forum information and some related Jaguar manuals, I overhaul two distributors and two amplifiers for my XJ6 S3 and a third system as a retrofit to my 3.8S sedan. One distributor and amplifier are spare units.

My 1984 XJ6 S3 always had a small stutter at idle; and parts for the Malloy Unilite Distributor retrofitted to my 1965 3.8S Sedan in the mid-80s are no longer available. Using the Forum posts recommendations for XJ6 S3 Trouble Shooting, I changed vacuum lines, sent out fuel injectors for cleaning, plugs, wires, grounds, AFM etc.; all needing attention, but did not resolve the stutter. Finally found upper bearing in distributor worn to the point where the rotor was intermittently hitting the pickup at idle. Could not find a replacement Distributor, so began the process of looking for distributor overhaul instructions and source of for internal parts. I could not find overhaul instructions or even detail specifications for the distributor (LU-45DM6 P/N 41912A). It appears that Jaguar did not intend the distributor to be repaired/overhauled, just replaced. Cap, Rotor, Anti-flash shield, Pick-up, Vacuum advance and O-Ring are available. See attached Illustrated Parts List; use foot note (4) configuration. AEU1703 Advance units are late US only, and harder to find.

There is an aftermarket Pertronix distributor P/N 177600, but it will not fire the Fuel Injection System of the XJ6 S3, should be fine for a XJ6 S1 or S2. Installed this distributor on my 1968 XKE S1.5 and it performed well. I did the research and found you could use the Pertronix P/N 177600 distributor on XJ6 EFI engine, if you add a MSD Digital 6A ignition controller (P/N 6201) and their proprietary Tach/EFI Adapter (P/N 8910). (the Lucas AB14 Amplifier is not required for this setup). Initial 8 degrees static recommendation should be adjusted to 10 degrees for EFI setup with 8.7:1 CR using 87 octane fuel. (See PDF Advance Curves attached)

I found used XJ6 S3 distributors and AB14 amplifiers cores on E-bay for under $100 and $70 respectively. Stay away from distributors with stiff or seized bearings. A sloppy bearing can be replaced, but a seized upper bearing (lower bearing is well lubricated) will ruin the shaft and may even have spun the bushing in the aluminum case. Many units will have stuck advance units from OEM grease hardening or corrosion. The vacuum unit will have failed or just about to fail from age hardening of diaphragm. If you want to repair yourself, Jaguar and Triumph forum posts on distributor disassembly and cleaning are very good; Be extra careful not to stretch centrifugal advance springs during disassembly. I could not find part numbers, a source (USA or UK) or, the specifications for the two advance springs. One spring controls the early part of the advance cure, both springs together control the later stage of the advance curve. If you do the distributor repair yourself, you will not be able to test distributor before installation on your XJ6.

My recommendations:
1. Send the distributor to one of the Lucas Distributors Overhaul Specialty Shops, they have the test equipment, many detailed parts and may be able to repair internal parts that are no longer available. The Distributor will be “better than new” when you get it back. They can make small adjustments for optimum performance and reliability given modern fuel octane numbers. You will get a “bench tested” proper advance curve for your engine configuration. {Jeff at advanceddistributors.com} or {Martin at distributordoctor.com.}

2. Overhaul the AB14 Amplifier yourself, it will outperform the original unit.

3. Upgrade the Ignition Coil (.6~.9 ohm), Ignition Wires (7mm; Mag Core; Silicone Jacket) and Spark Plugs (NGK non-resistance) to modern specifications.

4. Have your AAA towing insurance upgraded from 5 to 100 miles. Good Jaguar shops for XJ6 S1-S3 are getting rare and far between.

I have attached a PDF showing some details of the Amplifier Overhaul. The Black Text and pictures are from previous forum posts; The Red Text and a few of the pictures are from my notes.

God Bless Jaguar Owners

 

Very helpful.

Not having any issues now other than a slightly lumpy idle, but this is so complete and descriptive, I think I'll make a 'preemptive' repair of the ignition module to head off the inevitable amplifier failure

I printed a copy and put it with my Jaguar documentation too - want to have it at hand if I'm lazy and don't get the mod done before it fails

Thanks again,

 

What about the pertronix D171618? That supposedly works with the injected models, no?

 

On the six cylinder cars, the only link between the EFI system and the Series 3 ignition system is a wire from the coil to the EFI box. This provides a pulse so the EFI system knows when to fire the injectors. They all fire together twice per engine revolution. So the Pertronix disributor should have no effect on the EFI system. The Lucas EFI system for the siz cylinder cars is actually the Bosch L-Jetronic system made under licence, the V12s being D-Jetronic.

 

Fraser,
I check this out with Pertronix to see if I could electronically make it work, this was their E-mail response. Others explained that the Pertronix pulse wave is incorrect for the Bosch/Jaguar Computer. The MSD Tach/EFI adapter was to correct the Pulse, as they initially had problems with Bosch EFI and their 6A Ignition controller.
Rgds David



"MARVIN,
PerTronix Inc.

The D177600 distributor specs say it is for pre-EFI jaguar XJ6 S2 engines. Is there a physical or electronic reason it doesn't work on EFI XJ6 S3 engines?
Thanks
David McElroy

Response from Tech Department

The Ignitor will not trigger the EFI system.

Marvin Grebow Jr.
PerTronix Inc.
Technical Department
909-273-6006
marving@pertronix.com

 

I would not be able use in California car so did not check this out.

PerTronix D171618 Flame-Thrower Electronic Distributor Performance Distributors for British Engines Flame-Thrower HP distributors take the performance line of distributors one step higher. That's right, HP stands for High Performance, and that's what you get with our all new HP distributors. These distributors feature patented Ignitor II technology and are available with top exit or our new side exit caps......... Not legal for sale or use on pollution controlled motor vehicles.

 

 

I also got same feed back from XKS unlimited, when trying to solve the lack of OEM support for the S3 distributor. See first paragraph of attached Page from their catalog. Rgds David

 

Tar... Thinking about your comment that there have been D177600 Distributors successfully retrofitted to XJ6 S3 EFI Cars; Could be that Pertronix didn't want the expense of getting California approval for a limited market, choosing only to market Distributor as a replacement for carburetor XJ6 cars, or with a 3.0 ohm ignition coil specified, the performance appears to be slightly less than that of the OEM CEI system when new, again choosing not to market it as a direct replacement???
The Distributor was definitely an improvement over the points system. I installed a D177600 on my 1968 XKE and was very happy with it. Rgds David

 

Tar... Thinking about your comment that there have been D177600 Distributors successfully retrofitted to XJ6 S3 EFI Cars; Could be that Pertronix didn't want the expense of getting California approval for a limited market, choosing only to market Distributor as a replacement for carburetor XJ6 cars, or with a 3.0 ohm ignition coil specified, the performance appears to be slightly less than that of the OEM CEI system when new, again choosing not to market it as a direct replacement???
The Distributor was definitely an improvement over the points system. I installed a D177600 on my 1968 XKE and was very happy with it. Rgds David

Reference my comment that the 3.0 ohm ignition coil paired with the D177600 distributor may not be considered a direct replacement for the XJ6 S3 original Lucas CEI system: Please see the attached 2015 two page summary from Triumph site, on replacing a Lu-25D distributor with a Lu- 45DM4 (CEI) ignition system. The full paper is 30 plus pages long and reads like a college dissertation. Full article can be googled if interested.
This was in my notes folder on retrofit of the XJ6 S3 ignition system to my 3.8S. Rgds David

 

Thats the one I am using on my '86.

 

Greg, I looked up specs; Definitely the the D171618 distributor with the 3673 ignition coil has the performance. 3673 is same ignition coil I used with the new pertronix D72000 pin module in my AB14 amplifier. I am going to see if it is line to get California approvals. Rgds David

 

Greg,
I checked with XKs Unlimited and Summit Racing, both listing the D171618 distributor for sale. XKs still shows a note for Carburetor XJ6s only, and a call confirmed that they recommend it for E-Types. Summit shows it for British cars, but then asks you to enter your vehicle info confirmation fit: entered 84-85-86 XJ6 and each time, said does not fit your vehicle. At the bottom of spec sheet there is a link to California Approval Documents and tells you to confirm approval for your vehicle. ARB > Executive Orders > D-57-23 . California approvals for Pertronix distributors are listed for 1995 and older Chrysler, GMM and Ford V8s and 6 cylinder models; AMC and Volkswagen model are also on List. I checked the California approvals for Pertronix ignition models: ARB > Executive Orders > D-57-22 All of the Pertronix Ignitor models are approved for ALL 1995 and older vehicles with points distributors.

No joy for Californians, but since there are numerous reports of successful Pertronix installations on EFI XJ6s,
The D171618 Distributor is definitely is a worthy replacement for OEM Distributor & Amplifier ( cost & performance) .
Thanks David

 

Forgive my ignorance on emissions requirements in California (thankfully cars over 25 years old get a free pass in Georgia - for now anyhow) but do they really go down to the level of checking which distributor you're running?

 

The tech's at the smog stations peering down between the Air filter, fuel rail and Cylinder head would never know what he is looking at, so they put the burden on Amazon, Summit, Jeggs not to sell anything into California that is not approved. The approved Pertronix HEI module came with a CA decal that goes on the hood next to Jaguar Emissions sticker. If you have a problem on test, real or imaginary, you go a "referee smog station" that is more experienced on your car type.
I was actually more concerned back then, with the comments that it would not trigger the EFI computer properly. What I might have done myself, I would not advise others to do if it wasn't 100%. So it is like the mattress sticker that says " Do not remove under penalty of law"......California is "different", come January 2019, Pet Stores can no longer sell pet Rabbits, and restaurants don't give out soda straws unless you ask. Rgds David

 

CA, oh yeah!!!! And more in the offing.

1. New Guv is nuttier than the last one.
2. The D's now have a super majority in the legislature. they can now do what they d... well please.
3. My district just lost the voice or reason for a "progressive" assembly person.

If the Pertronix is the insert withion the Jaguar unit, the smog guy will never know... And, most not really care. There main concern is the ARB spy car...

Even the entire distributor will likely get by the average SMOG.

CARB is interested in only and change in timing changes. The Jag curve has suited them . Any other might be different and not tested to please them. Way back when, the "fix" was to alter the vacuum advance to get a late fire at idle. .

I surely am not on par with the Pertronix techs as to the pulse match?? Six cylinder engine, six pulses pre distributor rotation?? By pointsa nand condenser, GM modue or pertromix ,odue…

Yes. ARB prefers the Pertromix Lots of those around, huh!!!!!


Helful tech lady ATT got my cell back up and running...

Carl