How to... connect coil of XJ6 S2 1978 carburetted (latest S2)?

Hi guys, nice to meet you all.

I have bought a 1978 caby jag 4.2 series 2. The engine was out the bay.
I have rebuild the engine, and as upgrade, i decided to install a powerspark high ignition distributor.
From the engine harness, i connect the white and the white/blue wire to pos pin coil (ballast resistor eliminated). To the neg pin, i connect the blue/white/grey and the white/black from wiring harness.
By the side of the dist, red wire to pos, black wire to the neg. Negative ground is nected too.
With this, sometimes i have spark, sometimes, no. What is wrong?
Could yo be kindly to attach images about your ignition system wiring? My english is not so good, and a picture draws more than a hundred words.
Thanks in advance to all, guys.

A ‘powerspark high ignition distributor’ is a somewhat vague description, Pedro…:slight_smile:

For proper advice; we need the precise ‘name’ of the distributor. And the function and connection of its wire colours from the dist should be in the dist instruction manual…?

First question; does the engine crank only in ‘crank’ (not with ign just ‘on’) - and does it catch/run at all?

Basically; a self contained electronic distributor has two wires; one to coil pos and one to coil neg. Red and black, respectively, sounds reasonable…so far…if(!) there are only two wires from the dist…

However, the car wiring in your case has several functions involving the resistor pack (not a single resistor) and other items - your connections are unlikely to work properly. Whether others have a similar conversion on a 78 depends on which electronic dist you have fitted…

All that said; keep the dist wires as is and car’s white wire connected to the coil pos - disconnect all other car wires. Then try starting - and see what happens.

Then we’ll see…

xj6 85 Sov Europe (UK/NZ)

Hi Frank.
Thanks for your answer.
In fact, the distributor bought is called" powerspark"|Model%3AXJ|Cars+Type%3A6+4.2|Cars+Year%3A1978|Plat_Gen%3A--|Variant%3A--+[1968-1996]+Saloon&epid=28021730402&hash=item1c14784a7c:g:Cj4AAOSwJpda0K6r it comes with plugs, leads and viper coil too. All compatible.
Of course, it has two wires, one red to the pos, one black to the neg.
The engine just crank in “crank”.

I will check the gap between ring and module again… How many mm must it have?

White wire to de pos coil, red wire to de pos coil and black to the neg is a good advice. Ill try on saturday morning (my car is not close to me).

Does someone have a image of their ignition wiring harness ?

Thanks a lot


pictures of our cars won’t help you as you have decided to take another route when choosing the Powerspark distributor. Which installation instructions came with the distributor? From the site you linked I found this instruction:

There seems to be no white wire - only red and black and they go to the coil.
If you have done this and the Powerspark is o.k., everything should be fine. If the engine doesn’t fire or doesn’t have spark I’d suspect the coil (is it o.k., is it the right one, is it compatible with the Powerspark distributor?) or the ballast resistor that may or may not be needed or even be bad for the spark. Anyway, if you pull the center plug at the distributor cap you should have a good spark to begin with - after all the distributor only distributes.

BTW, the parts catalogue indicates the following setup:

Good luck

75 XJ6L 4.2 auto (UK spec)

What ‘ring and module’ would that be, Pedro…?

With an electronic dist like yours; the dist red and black wires, and the white car wire providing power from ignition key, is all the wiring required for ignition. The other wires serves other purposes, and their functions are either redundant with the electronic dist or require clarification before connecting them to anything…:slight_smile:

Testing out the basic set-up described, will eventually show up what’s missing. I suspect that the tacho won’t work - it is probably related to one of the other car wires mentioned. However, the tacho you have may not be directly suitable for use with that electronic distributor…

xj6 85 Sov Europe (UK/NZ)

Hi guys.
Thanks to all for your answers.
As i told you, i just have time on saturdays to work on the jag. Yesterday checked everything and i discovered a problem with the earth continuity on the new distributor.
I fixed the old coil and the old dist and… runs.
I will send an email to the dist seller to explain my problem and i hope to solve with him.
Thanks again. You are a great community and im proud to be here

Frank. When i told you ring and module, i meant this

Excuse my english. Thanks Frank.

No explanation from the manufacturer of its function, Pedro - and where it is supposed to be fitted…?

xj6 85 Sov Europe (UK/NZ)

Hi Frank.
Ring goes on the axle of the distributor. Module eliminates contact points and condenser.

Which means that the black ‘thingy’ fits over the cam inside the dist, Pedro…?

Which indeed means that the distance between the ‘red’ and the ‘black’ thingies is critical and adjustable…?

xj6 85 Sov Europe (UK/NZ)

Sure! I think so. Black “thingy” is a magnetic ring. Red “thingy” is the electronic module. Is not so technical vocabulary… hahaha

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That‘s a hall sensor. Adjustment probably comparable to the S3 system, which uses a toothed ring as source. Distance should be mentioned by pertronics, very close, not mm’s! when everything is installed, set the engine to the specified advance on the flywheel and not one revolution out and place the lead from the coil a few tenths away from the ground. Now turn the distributor until it sparks. Then you‘ve adjusted the timing/ module placement.
Now that it runs, this might clarify.

Hi, I bought two XJ6 4.2 series2 -(non runers)for restoration. On both cars is no spark on plugs. Coil is connected different: one car has black whire (from blue resistor )on negative -connector other on positive+… can someone explain please what is correct…

[quote=“zarnca, post:12, topic:377276, full:true”]
Hi, I bought two XJ6 4.2 series2 -(non runers)for restoration. On both cars is no spark on plugs. Coil is connected different: one car has black whire (from blue resistor )on negative -connector other on positive+… can someone explain please what is correct…

What ignition systems are fitted, zarnca? And what wires do you have on the distributor?

Basic coil wiring on points equipped dists involves white wire to coil ‘+’, power from ign key. And a black/white wire to dist from coil ‘-’, and a black wire, direct ground, from dist to ground.

While turning; the dist/points alternately connects coil ‘-’ to ground to ‘charge’ the coil - and breaks coil ground to discharge coil. The discharge occurs as the points open - at which time the rotor points to the respective plugs with the required advance…

From those basics, things’ were added; an external coil resistor, bypassed in ‘crank’, required extra wiring. Sometimes incorporated with the starting relay - more wires. And to accommodate the tacho further arrangements were necessary.

With electronic ignition; further wiring were required though the basic function of the dist and coil were the same - the EI just did the coil ‘-’ switching electronically, But more/different wiring were required.

So the difference in wiring between your two cars is not surprising - adding that POs may have added or subtracted something.

So ‘no spark’ at plugs can have a variety of reasons - and require some clarifications…:slight_smile:

xj6 85 Sov Europe (UK/NZ)