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Ballast delete for electronic ignition?

Discussion in 'Rover P6 Electrics' started by GJM, May 19, 2018.

  1. GJM

    GJM Member

    Hi all,

    I've just purchased a Pertronix 2 ignition kit with a Flamethrower 12v coil to make the most of it.

    Obviously I could just take a 12v live from the washer motor to power the kit but I'd like to use the 12v coil to give the kit best performance.

    How do I go about bypassing the Ballast wire? Where does it run from and do I simply disconnect it and run new wire from its source to the coil? What amp wire should I use?

    1977 2200TC
  2. colnerov

    colnerov Well-Known Member

    Hi, The coil supply comes from the ignition switch through the tacho then the ballast wire to the coil. Traditionally it is unfused because if something on the fuse has a problem and blows it. Do you want to be fault finding trying to find out what blew the fuse before you can get the engine working again? If it's anything like my luck sometimes it will be pitch black and tipping down with rain in the middle of nowhere, very testing. So run a new wire from the ignition switch depending on what type of tacho you have it may or may not work. 10 amp wire will be more than enough.

    PeterZRH and rockdemon like this.
  3. GJM

    GJM Member

    Thanks Colin. I've not had a look at the wiring yet but would it not be better to leave the tacho connected to the ignition and replace the ballast from the back of the tacho to the coil? Thus leaving the tacho wired in?
  4. colnerov

    colnerov Well-Known Member

    Hi, If you don't mind unwrapping the loom because it's a resistor wire within the loom, then yes.

  5. GJM

    GJM Member

    Ah okidoki. Hence the risk of the tacho no longer functioning. Got ya.
  6. GJM

    GJM Member

    So I'm going to hopefully have a look at this tomorrow. See if I can locate the white/yellow (or pink) from the back of the tacho, unplug, run some new 10 amp wire from there are connect to the new 12v Petronix Flamethrower coil to power the Ignitor 2 kit.
  7. Willy Eckerslyke

    Willy Eckerslyke Well-Known Member

    Easiest way to forget the Flamethrower coil and retain your old one. Then you just need 12v to the Ignitor unit taken from somewhere controlled by the ignition switch (I used the blower circuit, plugging into the connection that conveniently tucked behind the wiper motor). At the very least you could start this way to get the electronic ignition system working and decide later whether you need the fancy coil. You won't need to cut any wires.

    I understand Colin's concern about using a fused supply but it's worked perfectly for me for well over ten years.
  8. cobraboy

    cobraboy Well-Known Member

    The original ignition feed goes through a fuse, ok it has its own fuse, but still through a fuse. I just piggy backed off the washer motor to go 12v, If I get an issue with that fuse blowing I will just plug the resistor wire back on the coil to get home, it will still run with a reduced quality spark.
  9. GJM

    GJM Member

    So had a look yesterday. There is two white/yellow wires running to the +Coil. One thick, one thin. I presume the thick one runs to the starter motor and the thin one is the ballast to the tacho? If so do I remove both and run a single wire to the back of the tacho? Or just remove one off them? Thicker 12v to the starter and replace for a new 12v switched?
  10. colnerov

    colnerov Well-Known Member

    Hi, If you're going to run a 12v coil you don't need the ballast bypass from the starter, so remove both and run replacement wire from the tacho.

  11. GJM

    GJM Member

    Cool thanks Colin.

    So I presume the starter has its own power from elsewhere if I disconnect it from the coil.

    I'll take a look at the back of the tacho and see if I can run some 10 amp wire to the +coil having disconnected both W/Y wires from the coil.
    This should mean the 12v coil gets the 12v it needs and the tacho can still see it as well.

    I made up a new cable yesterday, but ran it from post 19 on the back of the fuse box into the engine bay thinking I'd just run the leccy ignition with the original ballast coil. I've since decided to use the new 12v coil hence wanting to rid myself of the ballast again.

    Can I just run the new wire from the back of the tacho to the coil or could I run this switched 12v cable from fuse 19, to the tacho, then to the coil?

    I'm obviously a bit of an electronics novice and every time someone talks about the ballast it seems different to how others have described it :)
  12. eightofthem

    eightofthem Member

    Just a bump on this thread, after fitting a replacement electronic distributor and matching coil, I now need to have the tacho working again.
    At the moment it is wired as per the old points system to get it up and running
    The White / grey tracer wire from the tacho is fitted to the - side of the coil
    Both White / yellow trace wires from the tacho to the starter ( large and small wire ) are fitted to the + side of the coil
    The dizzy wire goes straight to the + side of the coil, where before with the points type dizzy the wire was connected to white / black trace from the tacho.
    So can the tacho be wired in to work?, or is the RVI type / RVC type at play here?

    Incidently I could not find a mention of the White / grey trace wire in any diagrams
  13. colnerov

    colnerov Well-Known Member

    Hi, I found some of the previous threads on here using google search. There was also a quick note that says "RVI for points ign, RVC for electronic Ign".

    RVC tacho conversion

    RV1 and RVC Tachometers

    Lumenition Optronic affecting tacho

    Hope this helps.


    P.S. ISTR the white/slate wire is referring to SD1 wiring, but I can't find my SD1 book at the moment.

    Edit: If you do a google image search for "RVI RVC tacho" it brings up thread/posts about retro fitting a PCB into the tacho to convert.
    Last edited: Jun 13, 2018
  14. eightofthem

    eightofthem Member

    Thank you for the links ;)

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