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Ford/GM HEI coil question

Discussion in 'The Hokey Ass Message Board' started by gotmark73, Aug 16, 2011.

  1. Morrisman
    Joined: Dec 9, 2003
    Posts: 1,600

    Morrisman
    Member
    from England

    They use this same system on the UK version of the Buick 215, except the amp is stuffed inside an aluminum box of tricks, several little devices that don't seem to perform any function.

    [​IMG]

    I ripped all the junk out, bolted the amp to the outside of the box, which also mounts the coil, and bolted it inside the car, rather than out in the engine bay.

    [​IMG]

    You have two wires from the dizzy to the amp, then two from the amp to the coil, and you provide ignition-switched 12 volts to the coil. Simple, no need for fancy relays or connectors etc.
     
  2. pie pie
    Joined: Jun 29, 2008
    Posts: 673

    pie pie
    Member
    from missouri

    I like the swap. I used the ford coil for the performance and price
     
  3. REM/Mo
    Joined: Feb 24, 2008
    Posts: 281

    REM/Mo
    Member
    from Missouri

    Please explain.
    In this wiring diagram it looks like this is powering the coil with 12v when the switch is off and dropping the power to the coil and powering the module terminal B when the switch is on.
    What am I missing here.
    Thanks.
    I plan to use this set up on my "60 T'bird and would like to use a relatively stock looking coil.

     
  4. 52Poncho
    Joined: Apr 23, 2011
    Posts: 256

    52Poncho
    Member

    When 85 is powered and 86 is grounded, 30 powers 87 and 87A.
    When 85 is open (off) and 86 grounded, 30 is open to 87 an 87A (no power).
     
  5. Can I mount the module panel under dash, and run wiring to the front mount distributor? Or is it too long a run of wiring?
     
  6. 52Poncho
    Joined: Apr 23, 2011
    Posts: 256

    52Poncho
    Member


    Yes you can but try to keep the wire run as short as possible and it would be a good idea to twist the insulated wires from the pickup coil together and keep them away from other wiring to stop crossover (not tied together with power wires). Shielding the two wires from the pickup coil would also give you a little more length if you run into degradation of signal. The "B" and "C" terminal wiring should be OK under the dash. The Ford pickup and GM pickup should be fine (strong signal), the Chrysler pickup is a little weaker signal and may vary in length in comparison.
    Bubba may have some data on this.
     
    Last edited: Aug 18, 2011
  7. 52Poncho
    Joined: Apr 23, 2011
    Posts: 256

    52Poncho
    Member

    Just thinking about maybe placing the coil and module hidden in or around the rad shroud maybe an alternative to a shorter length for the pick coil in the front mounted dist. Food for thought.
     
  8. REM/Mo
    Joined: Feb 24, 2008
    Posts: 281

    REM/Mo
    Member
    from Missouri


    When 85 is powered and 86 grounded the relay is energized and 30 powers 87.

    When 85 is NOT powered the relay is not energized and 30 powers 87a.
     
  9. mustangsix
    Joined: Mar 7, 2005
    Posts: 1,296

    mustangsix
    Member

    Now that I look at it, the relay hookup doesn't make sense to me.

    Turning on the ignition powers the module, but does not power the coil. Turning off the ignition powers up the coil, but shuts down the module.

    If you intend to use a relay, shouldn't it power both when the ignition is on? Otherwise, how would it work?
     
  10. 52Poncho
    Joined: Apr 23, 2011
    Posts: 256

    52Poncho
    Member

    Greenbird56 said it was a NO Relay, so 87 and 87a should be open when no power to 85 and 87 and 87a powered when 85 is powered. You must be careful about what relay you get. If 87a is powered (NO/NC Relay) when open then both connections will need to be connected to 87 terminal and not 87a.

    Read this:
    http://www.eurekaboy.com/f250/relay101.htm
     
    Last edited: Aug 18, 2011
  11. gotmark73
    Joined: May 14, 2008
    Posts: 144

    gotmark73
    Member

    Poncho, I have read your explanation of the GM coil wiring and compared it to the drawing posted. Am I correct to assume that the coil takes keyed hot in and passes it to the module? In the diagram it seem that hot is wired to both the coil and the module.
     
  12. GMC BUBBA
    Joined: Jun 15, 2006
    Posts: 3,384

    GMC BUBBA
    Member

    Yes the coil and the module must be supplied with the same 12 volt battery feed.:)
     
  13. 52Poncho
    Joined: Apr 23, 2011
    Posts: 256

    52Poncho
    Member

    Yes as Bubba states the module and the coil are powered by the same feed. The large pink and the small pink are connected inside the coil, therefore have the same feed. You only need to connect the large pink to your 12v source, the small pink will power the module to the "B" connector.

    I see what you mean, if you use this GM coil with the relay you will only need to connect the 87 terminal to the coil in this instance, the 87a will not be needed.
     
    Last edited: Aug 18, 2011
  14. gotmark73
    Joined: May 14, 2008
    Posts: 144

    gotmark73
    Member

    Thank both you guys, gotta hit a pick a part for a coil so I can make some progress on the car.
     
  15. fastair
    Joined: Sep 17, 2008
    Posts: 7

    fastair
    Member

    Have been following this thread with great interest as I am in the process of putting together a little 302 for my slick 60 truck. I have built the module and heat sink as Greenbird56 had in his post, found a .5 ohm coil and ordered a duraspark distributor from Autozone. Here is where my problem starts. The distributor that came out of the TBI 302 (year unknown) that I am using had nothing inside except the rotor and the shaft length below the gear is 1 1/2". All of the duraspark distributors I have been able to find have only a 1" shaft length below the gear. Does anyone know of a duraspark with a longer shaft or is there another longer length of oil pump drive I can use? The duraspark will engage the existing oil pump drive but it is 1/2" shorter than the original distributor. Is this engagement enough?

    Thanks
     
  16. chicken
    Joined: Aug 15, 2004
    Posts: 163

    chicken
    Member
    from Kansas

    Yes,it does engage the oil pump drive enough. We've run several race engines this way with no problems,and I have a street engine with this setup as well. Not sure why Ford lengthened the dist shaft but they left the same pump drive as the older setup always ran. It'll be just fine.

    chicken
     
  17. fastair
    Joined: Sep 17, 2008
    Posts: 7

    fastair
    Member

    Thanks Chicken, guess if it runs in your race engine it'll work in my daily driver.
     
  18. I'm glad you guys got the N.O. two post relay figured out - I was away for awhile and missed out. Be really aware of the grounding of this sort of outfit. Ford's original plug attachment to the distributor carried the ground back to the distributor housing from the module - and according to the old Ford service bulletins I got my hands on, that wasn't always a reliable, full engine block ground. An imperfect ground will cause some electrical problems for sure - so think seriously about a ground to the engine block that exits the distributor and screws down tight. It will just about guarantee that you will get all of the AMPs and Volts you deserve.

    I run my HEI module with an MSD "Streetfire" TFI coil (.44 OHMs) - it will light up your life. And when the Ford Duraspark II controller is on there (in some climates the 6° starting retard is a nice wintertime feature) I use a ballast resistor to move total OHMs over toward 1.5. The Ford module uses a fixed 26° dwell - and basically provides the same performance as a set of points. I wired it all up using the Ford plug conectors so the serviceability design still worked - swap modules in minutes with no burned fingers.
     
  19. Morrisman
    Joined: Dec 9, 2003
    Posts: 1,600

    Morrisman
    Member
    from England

    It worked okay in mine, in the pics above. The coil wires were no longer than they had been when the whole shebang was mounted on the inner fender. But it runs a lot cooler inside the cab.
     
  20. GMC BUBBA
    Joined: Jun 15, 2006
    Posts: 3,384

    GMC BUBBA
    Member

    Good thread guys.
    Some info regarding wiring length.

    The oem (some variation with the aftermarket,some improvement. Some not)
    Control module turns on using a .250 volt (250 mili volts) and the ford dura spark can deliver this at a very low cranking speed. The dura spark signal could be 10-14 volts at 2500 rpm !
    With this strong of a signal, the loss (if any) with wire length more than likely wound not be a concern.....
    Also the signal is polarity sensitive, as the GM module needs to turn on with a positive signal and off with a negative (dwell control). If car runs bad after a repair etc, reverse pickup wires......
     
  21. Realist
    Joined: May 3, 2009
    Posts: 17

    Realist
    Member

    I respectfully submit a question, regarding the illustration posted by Greenbird:

    Number 30 terminal, on the relay, is hot all the time and, since 87A is normally closed, the positive wire to the coil would be hot, according to this illustration., (with the ignition switch off).

    However, when the relay's activation coil is energized, by sending current through terminals 86 and 85, the internal contacts of the relay moves from 87A, to 87. At that time, 87A ceases to send current to the coil! The current flow, will now only be between 30 and 87, which by-passes the coil!
    ( There is now an open circuit between 30 and 87A)

    The way I see it, there's no way this is going to work, because, there is no longer any current available at the positive post of the coil. The continuity is now between 87 and the module, but with no power to he coil!

    Am I missing something?
     

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