Hi guys

Not sure if this has been done before but i thought this might be a good avenue to post a picture of a part of your engine your curious about.

I'll go first....

I'm curious about the Ignition Amplifier. (Ok so I know the name of the part only cause its written on it lol). I figured as the name suggests it amplifies the electronic signal from the ignition (right?). Can somebody elaborate? Why is it needed?

I noticed mine has been moved right in front of the grill, behind the LHD headlight. Looking at a Jaguar book I own at home, I noticed on a brand new 1981 HE V12 (see pic) it was mounted on the engine. I can see on mine the old mounts where it used to be. Was this a common mod? Did this component used to get damaged there?

Would love to know more and also hear about your engine parts your not so sure about.

Cheers.

 

HA.

Another Grant mod.

I do that to all that ask, as the heat and the amp are NOT friendly. Mine has lived out there for 20+ years, and never an issue. The Goose has been there for 10+ years.

It is an electronic replacement for "Ignition Contact Points", AND it does other things on the V12 as well, such as "tell" the ECU to fire the injectors, and keep the fuel pump running. Also sends a trigger for the Tacho.

Bad earths, heat are it main killer.

Now "Ignituon Contact Points" may need explaining via Google for some of the newer generation who have totally missed out on the absolute joy of maintaining Contact Points. I dont miss them one bit.

 

I have a set, but never had to take the dissy cap off the car yet.
That it is a job listed to do with the next oil change. Haven't had a car with points until this one since I sold my 1966 HR ute back in 97"

 

The mighty HR.

So you know what points are and how to sort them, we are a dying breed young man.

Magneto's are the curly ones.

 

This is a great idea Paulying, I can't wait to get under the hood and start snapping pictures, there are a lot of mysterious parts under there

 

I do miss the simplicity of a points system. They could be serviced anywhere with almost anything. I still have an old dual point dist in one of my parts boxes I'm saving for something.
Gap and dwell

 

Cheers Grant

So, the ignition amplifier replaces the need for a contact breaker like in the simplified diagram below?

As I understand it, the contact breaker creates a collapsing field in the Ignition Coil's primary winding, causing a high voltage in the secondary winding of the coil, which then goes to the distributor and gets "distributed" to each spark plug right?

What are you guys calling the dizzy cap though? I thought that was referring to the rotating arm inside the distributor cap?

The 1985 XJS still uses the other components of the simplified system below right? (Still has ignition coil and distributor?)

So Grant I can see why It used to be mounted near the coil. For such a critical component it was strange that they just mounted it on top like that exposed to all that heat! So I am guessing you would of had to extend the wires a fair bit to make it out to the front.

Ha ha, with one question creates more questions.

Again thanks for your time guys, especially the Wizard of Oz

 

If you open the box up you will see Jaguar used a four prong GM, HEI ignition module to do the job. The module lives inside of the HEI (high energy ignition) distributor on GM cars which is not the friendliest of environments. On XJ6 series III's they reside in a similar box on the front of the engine block. I've yet to have one fail installed where Jaguar intended but as a course of good thrift I replace mine at tune up time as they are not expensive. It is imperative when replacing the module to put a good coat of silicone heat sink grease between the base and the box because I do know from experience on a chevy pickup I had they won't last long without it. Having it out front in the breeze certainly won't hurt it any.

 

Paul,

The dizzy cap (distributor cap) on the Goose, is the large Blue cover on top of the distributor what the spark plug wires plug into.

The rotor is often called the "Rotor Button" as the real early designs were of that shape in a strange way, and it has stuck.

Also of note, inside the cap, and protruding from the centre post (coil lead post), is a "carbon contact brush", and the V12 can destroy them. I have replaced many over the years, and being in OZ, your local Holden dealer has them as a GM part, cool.

Many theories, damn I luv them, as to why it was mounted on the inlet manifold. The large alloy mass is a good earth path, yep, I can see that.

The intake air keeps that mass cool, and so cools the amp, HAHAHA, try putting your hand on that mass after 15 minutes with the bonnet shut, good luck.

Extending it is simple, wire is wire, and connections is connections, simple, and the coaxial cable (the Goose still got one of them) is simple TV antenna cable, damn these are simple cars, mmmm. Eliminating the coax, standard wire, soldered and heatshrink sealed.

Yep, ya still got coil/s and distributor. The X300 6ltr has Nippon Denso distributorless engine management. Never seen one in the flesh, just from when I was at Jaguar Parts, via the Parts Books.

 

Whoa! Great info Grant.Cheers.

So there is coax in there? As in the same cable used as your TV??( One copper conductor, an insulator and shield)Never heard of that used in automotive electrics. Must of originally used it to try and prevent harmonics or interference I guess.

 

Yep.

The original amp placement had the wiring traversing the rear LH corner of the engine, and very close to 6B spark plug, and not so close to 6A, and this was the answer in 1982. Worked just fine.

Only trouble is it got brittle, and the amount of pushing and shoving required to change V12 spark plugs, mainly the 2 rear on each side, had that loom, and others, geting cracked insulation, and then the Prince of Darkness found his way into the system, and the threads on Forums started.

"V12 wont start/ V12 runs strange, when it runs/Injectors not firing/ etc etc". Usually about 10 years after delivery.

My amp is out the front on the RH side, and the wiring runs up the inner guard, and across the top, behind the brake booster bracket, tucked up under the scuttle panel, and is nowhere near the spark plugs or anything else for that matter, and I run NO coax, until the RH loom bullkhead connector where I spliced into it again to get to the ECU, simply coz it was nice and pliable, and I was too lazy to run a fresh wire all the way to the rear.