Hello,

It is California XJ6C with original distribitor 45DE6 and 2 balast resistors. ( as I understood only USA cars has two of them)
The car is out of the road more than 30 years
(last SMOG from 1999), the distributor dont work
and we ordered new ignition set from SNG Barratt: 123 electronic distributor, new coil and leads.
The old distributor has 3 wires, WB to negative coil, RB to bottom of right resitor and WU ( white /blue) with bullet lucar connected to male bullet green wire comming from upper side of same right resistor. Arround wires and resitors there is empty double bullet green wire female lucar comming from main harmess.
I can’t find proper wiring diagram for this car,
but my logic is male to female green wire?
The new electronic 123 distribitor has only 2 wires, black and red.
We connected black to negative at new coil,
red to RB wire (bottom of right balast resistor)
The engine started without a problem, but tacho is not working ( I dont know if it has work with old distributor and wire connections).
So, I taked tacho gauge from dashboard and found two wires, WSU (white grau blue) and G (green). WSU conected to possitive at coil, green is the same empty double bullet green lucar.
Checked both wires, no interuptions, green wire is not connected to anything.
The questions are, do I realy need resistors with electronic distributor? How connect green wire to make tacho working?
The 123 ignition has 16 different MAP curves
(the table attached), wich one is propper for this engine?
BR
Stan

new ignition set

123 table

old distributor

balast resistors ( green wire with double bullet lucar is visible at left upper corner)

back side of tacho

 

Hello,
It is California XJ6C with original distribitor 45DE6 and 2 balast resistors. ( as I understood only USA cars has two of them)
The car is out of the road more than 30 years
(last SMOG from 1999), the distributor dont work
and we ordered new ignition set from SNG Barratt: 123 electronic distributor, new coil and leads.
The old distributor has 3 wires, WB to negative coil, RB to bottom of right resitor and WU ( white /blue) with bullet lucar connected to male bullet green wire comming from upper side of same right resistor. Arround wires and resitors there is empty double bullet green wire female lucar comming from main harmess.
I can’t find proper wiring diagram for this car,
but my logic is male to female green wire?
The new electronic 123 distribitor has only 2 wires, black and red.
We connected black to negative at new coil,
red to RB wire (bottom of right balast resistor)
The engine started without a problem, but tacho is not working ( I dont know if it has work with old distributor and wire connections).
So, I taked tacho gauge from dashboard and found two wires, WSU (white grau blue) and G (green). WSU conected to possitive at coil, green is the same empty double bullet green lucar.
Checked both wires, no interuptions, green wire is not connected to anything.
The questions are, do I realy need resistors with electronic distributor? How connect green wire to make tacho working?
The 123 ignition has 16 different MAP curves
(the table attached), wich one is propper for this engine?
BR Stan

A few answers are clear, others need more input...
-Curve 0 with an 10* static setting for distributor timing is a safe starting point (most of the curves are for heavily modified racing engines) ... follow 123 instructions for timing, not the Jaguar Hand Book. Two wires from 123 distributor to coil.
-The 123 Distributor and Ignition Coil do not need ballast resistors. (Tach may need a ballast resistor as Electrical Drawings are not clear.. cover US and UK cars)
Per Lucas distributor data your 45DE6 distributor is for a 1972 XJ6? is this what you have? I may be looking at wrong year diagram for the following:
-Wiring diagrams do not show (G) wire going to coil or ballast resistors, but do show a (G) wire going to the Tach, it is 12V input from fuse #4.
-There are 3 wires going to Ballast Resistor in the original configuration, one (WU) is coming from the starter circuit to increase voltage to coil when cranking. The second wire is (W) coming from ignition switch. The third wire goes to the Tach, but is not labeled... it is not the (G) wire that goes to Tach.
-Wires (W) and (WU) are 12 Volts input to + terminal of the new Ignition Coil. There should be a (WB) wire on negative terminal of new Coil that goes to EFI computer.
-From different Jaguar wiring diagrams; The resistor between coil and tach either a 6.8K or a 10K ohms resistor ( I think it will be coming from the (-) terminal of the new ignition coil. The three wire ballast resistor that you are removing had a 10K ohm resistor inline with the output to the tach. (can be placed at the tach or or line with wire coming off the new Ignition Coil)
If you give year and model info, others will be be able to direct you to the correct specific wiring diagram. I am reading with much difficulty out of a Haynes manual that covers all XJ6 models 1968 to 1986 US and UK.
Rgds
David

 

On the back of the tach, the green wire is power and the White/blue/grey is the signal wire. That should connect at the coil to the same terminal as the points.

 

Also, this is modern electronic system, so Spark Plugs and Wires are not the one called out as OEM recommended on Automotive web-sites ("does it fit?").. The ew Wires are resistance, the new plugs should be non-resistance. This was all about radio frequency interference (RFI) , not the quality of the spark.
Example: NGK 7832 BP5ES Nickel Spark Plug non-resistance.
Rgds
David

 

Hello,
Thanks for replies.
The car is XJ6C , 1975 first registration from California, with Stromberg carburetors and SMOG pump EGR etc...
So, finally, do I need those ballast/resistors?
I have checked: the green wire at tacho back has +11.5 V when engine is running,
SWU wire don't have break off from tacho to upper post of right ballast,
most probably Tacho is problem ?
How can I check Tacho itself ? Is there specific resistance between two tach posts ?
BR
STAN

 

Try this hook up:
Remove multiple wire resistor from circuit. Ignore G wire
To the Positive terminal of New ignition Coil attach the W and WU wires.
From new distributor: Red wire to Positive terminal, Black wire to Negative terminal.
To the Negative terminal of Ignition coil, attach new wire from small resistor, the other end of small resistor attach the tach signal wire (White/blue/grey)


Small Resistor
If you get Tach to operate good, if not, try by-passing small resistor with tach signal wire directly to Negative terminal of new Ignition coil.
after these tests, we can look into Tach malfunction itself.
Rgds
David
PS: Is the small brass nipple on the side of the distributor for the vacuum line? Where is the source of your vacuum coming from?

 

thanks David,
I will try it tomorrow,
its 11:00 PM in Bulgaria at the moment :-)
You are right, small brass pipe is distributor vacuum port. So far don't connect, still searching
vacuum diagram for XJ6, 1975 with Stromberg carbs and emission control.
As I know distributor must get vacuum from termo vacuum switch (ported vacuum), not direct from manifold? My termo vacuum switch has 4 ports, I don't know which one is in which one out.
Sorry for too many questions.
BR Stan

 

You are ok to hook Distributor direct to Manifold Vacuum source, you may have to add a connector in one of the existing manifold vacuum lines. Be sure to put a cap on all the other open vacuum nipples. This diagram maybe the one your car has.
Rgds
David

Connect line 1 to line 2, plug line 3

 

Hello,

update for tacho wiring…
As David suggested, rear (left) ballast eliminated,
front (right ballast) used only to connect WSU wire coming from tacho to negative post of the coil, nothing change, the tacho don’t work.
Even tried direct connection of WSU wire to negative coil, same result, the engine starting, but tacho is death. I believe the gauge itself has a problem. Is there specific procedure for checking of tacho gauge? Best regards, Stan

 

That is a Smiths RVC type tachometer, it is basically a frequency meter. You would need a frequency generator, 12v + and ground to test the tach. If you do a search on the RVC you will find a number of articles about them, circuit diagrams and videos of how to test.

 

https://www.triumphclub.co.nz/wp-con...dfs/Smiths.pdf

You may want to check the usual sources in your area for a used one known to work.
https://www.ebay.co.uk/itm/186368583869?
Rgds
David

 

Stan
Before opening the Tach for T/S, confirm wiring to tach is good.
Check signal wire from ignition coil to tach, no shorts or no open.
Check Green wire for 12 Volts with ignition switch on.
Check ground wire to tach has good ground on car.

With engine running 1500- 2000 RPM, sharply tap on tach to loosen pointer in its bearings.
Still not working, then inside Tach.
Drop of instrument/watch oil on pointer bearings
Look for loose wires or broken solder joint.
Unsolder and replace Capacitors and Diode, these are most likely failed components with age.
Rgds
David

 

Thanks David,
your willing to help, push me to solve the problem,
finally, the problem was missing ground/earth,
I connect additional wire from back side of the tacho to the dashboard and it's working now ;-)
As I read at the beginning with Jaguars, the fist and top important tools is multimeter and 12 V test lamp.
I can report the tacho is working in both cases, with WSU wire (coming from tacho) direct to negative coil post ,
or WSU to right/front ballast , then ballast to negative coil post. I stay with second connection through ballast.
Best Regards
Stan

 

Stan,
Always a good Jaguar day, when all finally works. your persistence at eliminating each potential issue and double checking, wins the day. Given the difficulty in matching a particular vehicle to the correct tech data, add an upgrade and you have a significant puzzle.
All the best, now that you are back on the road.
Rgds
David

 

Dear David,


The my XJ6C is out more than 30 years and
will be long way ahead before returning back on the road.
The engine is running, most of the electric issues addressed.
It is time for fuel tanks, brakes, then gearbox…
Thank you everybody for support, I will have much more questions.
BR
Stan