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Ford/GM HEI coil question

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

  1. gotmark73
    Joined: May 14, 2008
    Posts: 144

    gotmark73
    Member

    I believe some of you guys have done the conversion using a GM HEI module (the early 80's "boomerang" style) with a Ford distributor. I am in the process if building one. My question is what coil to use. I want a "cannister" type coil. I would apppreciate a part number, an application or barring that the ohm reading of the primary. I believe this is done without a ballast resister as the GM module takes care of that. NAPA has coils in stock but don't know which one I need.

    Mark
     
  2. mustangsix
    Joined: Mar 7, 2005
    Posts: 1,296

    mustangsix
    Member

    Stock HEI is less than 1 ohm, no ballast needed.

    Make sure you mount the module on a surface that makes a good heat sink and use the heat sink goo that comes with it.
     
  3. Mr48chev
    Joined: Dec 28, 2007
    Posts: 25,382

    Mr48chev
    ALLIANCE MEMBER

    The Hei and most all electronic ignitions need 12 V all the time hence no resistor.

    The heat sink goo that Mustang six mentioned is silicone dielectric grease available at any parts house.
    I'm not sure on the coil but you would want a non resistor coil. someone else might be able to produce a coil number that works good.
     
  4. That would make a good tech thread.
    Especially once you find the right coil.
     
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  5. burger
    Joined: Sep 19, 2002
    Posts: 2,347

    burger
    Member
    from burbs

    NAPA Echlin p/n IC-12 as recommended by Dave's Small Body HEI for doing this exact conversion
     
  6. burger
    Joined: Sep 19, 2002
    Posts: 2,347

    burger
    Member
    from burbs

  7. The grease used under the heatsinks is not the common stuff at the autoparts store - unless it plainly says it is for use on a heatsink. A lot of that stuff is actually brake caliper grease. Radio Shack sells this tube of "couplant grease" for a few bucks its worth having in the cabinet with the other specialty lubes....#276-1372A
    [​IMG]

    I think most race teams will tell you that oil filled coils are for antique cars.
     
  8. gotmark73
    Joined: May 14, 2008
    Posts: 144

    gotmark73
    Member

    Thank you all. I have never done a tech article (still too much to learn). Once I get the parts together I will do a write up. This is not my idea, I got the idea from the interweb, and everything was spelled out except the coil. I am hoping to have all the parts together in the next 10 days.

    Mark
     
  9. These are the necessary directions for wiring the Ford "Duraspark II" distributor trigger - to the HEI "four pin" controller.

    [​IMG]

    I would suggest you use relays to power the coil and controller - keeps both the voltage and amperage up - and if you use a "plug in" style relay, you can isolate it easily for service work. The little base block shown below makes mounting it handy - but other ideas work just as well.

    [​IMG]

    [​IMG]

    I like to use the Ford TFI style of "E-core" coil with this arrangement because they are (1) cheap at the yunk yard (with brackets) (2) epoxy filled (3) new clip-on connecters available at NAPA and (4) have about 1.2 OHMs primary - and easily hopped up with MSD or other "Mustang" coils.
     
  10. gotmark73
    Joined: May 14, 2008
    Posts: 144

    gotmark73
    Member

    Wow, thank you that is the clearest description I have seen yet for the conversion. I would like the round style coil for looks reason. With a little searching I found that the IC12 coil is 6v (needs a resistor) I am thinking the IC14 is correct without a ballast. Does this sound correct?
     
  11. For a round "traditional" coil, black, all position mounting - with no ballast resistor - use the Pertronix 40111. I think the price is right at about $35. The HEI "driver" transistor can easily handle the current of the 1.5 OHMs primary in that coil with the typical full "12v" voltage of 13-1/2 to 14-1/2 volts. It will be rugged - and look the way you want it to. The HEI will simply alter the "on" time" (dwell) to get everything the transistor can handle.
     
  12. GMC BUBBA
    Joined: Jun 15, 2006
    Posts: 3,344

    GMC BUBBA
    Member

    To get the HEI module to properly function and use all its features like current limiting ( at 5.5 amps-3.6 ms) you must use a .5 ohm coil.
    Although one of the better modules it also is a lazy module and will run with a higher ohm coil , it just wont go to current limiting control without the low ohm coil.
    Our USA made .3-.5 oil filled canister coil is $61 and we stock them .
     
  13. doozcoupe
    Joined: Mar 15, 2007
    Posts: 309

    doozcoupe
    Member

    The NAPA IC14 is the correct coil.
     
  14. GMC BUBBA
    Joined: Jun 15, 2006
    Posts: 3,344

    GMC BUBBA
    Member

    GUYS, some good info here , however there is some very bad info as well.
    IF it will help I can run a couple on a machine tomorrow with amp current waveforms of spark out put etc.

    I don't mind doing this as we have gotten this one stretched out a bit!
    The GM HEIcontroller is one of the best ever and works great with the dura spark input signal , however it needs a .5 or lower coil to make it do what it should! A higher resistance coil will lower the heis program output every time.

    Note

    The IC14 napa coil is. 3.25 ohms , the napa IC 12 coil is 1.5 ohms and should not be used with the hei controller if you want the features of the hei output etc.

    Stay tuned I will run some up on the tester tomorrow.

    I think we all need correct data here on the hamb board if possible .....:eek:
     
    Last edited: Aug 16, 2011


  15. GO FOR IT ! [​IMG]
     
  16. gotmark73
    Joined: May 14, 2008
    Posts: 144

    gotmark73
    Member

    Thank you all for the input, Bubba my older son just started school at Uindy so I will be making a lot of trips to Indy. I need to go see a carb guy also so I will come buy and pick up a coil and the half cover for the module. Hopfully in the next few weeks I will be down. Just to check, Bubba, your coil does not need a ballast?
     
  17. The GM module is almost bulletproof.
    We had 1 go bad between 3 cars with a total of 500,000 miles between them.
     
  18. GMC BUBBA
    Joined: Jun 15, 2006
    Posts: 3,344

    GMC BUBBA
    Member

    sTEVE ,

    gREAT JOB ON THE WIRING ETC, I SAVED A COPY FOR MY USE FOR SURE ...
     
  19. GMC BUBBA
    Joined: Jun 15, 2006
    Posts: 3,344

    GMC BUBBA
    Member

    OK, TOOK ME A MINUTE BUT NEEDED TO BE DONE I GUESS.

    The HEI came as a federal mandate to increase tune up mileage ( for clean emissions) and was a first from the Delco guys in regards to high energy ignition systems and was a home run from the first day forward.
    The ignition offered high energy at 5.5 to 6.0 amps of primary current controlled by the module. Module also offered a varying dwell to prevent the igntion coil from overheating using low dwell at idle ( 15 degrees) and increasing with rpm to 30 up the rpm scale.
    The orginal design was to use a .5 ohm untapped coil and isolated the primary and secondary windings ( caused some problems when left at high demand).
    This discussion concerns the ignition coils used with the HEI.
    I tested three coils this morning with the waveforms shown .
    1- .5 ohm (oil filled) ignition coil. Unit ws single firing a 25,000 test plug and used as waveform shows 5.8 amps clipped with current limiting ( hence the flat spot at shut of of control) and used a preset time of 3.6 mili sec to get er done. This is a normal function of a properly working high energy ignition system. You can hear see and smell the energy ( and feel if your not careful)
    2-1.5 ohm coil...... Unit still fires a 25 kv test plug but you can hear the difference in enegy, waveform shows a decrease in current to 3.0 amps . ( A new point ignition runs at this decreased level )
    3-4.0 ohm coil, would no longer fire the test plug and using a standard plug spark was at 2,000 volts and 1.5 amps .....this one wouldnt owrk very well if at all!

    Hope this clears up some mis conceptions in regards to HEI module control
    The hamb is a great place for sure.........:eek:
     

    Attached Files:

  20. gotmark73
    Joined: May 14, 2008
    Posts: 144

    gotmark73
    Member

    Thank you Bubba for the research and explanation. The HAMB never stops amazing me. I will be adding this info to my file of things I didn't know I needed to know. Thank you all again.

    Mark
     
  21. 52Poncho
    Joined: Apr 23, 2011
    Posts: 256

    52Poncho
    Member

    Bubba wouldn't the S10 Chev ignition coil work best for this application?

    [​IMG]

    48,000 volts maximum voltage, 85:1 turns ratio, 0.45 ohm primary resistance, 5.5 kilo-ohms secondary resistance.
     
  22. GMC BUBBA
    Joined: Jun 15, 2006
    Posts: 3,344

    GMC BUBBA
    Member


    Yes , would be perfect ( if you can stand the look ?) designed for the HEI controller for sure ........I would mount it under the dash with a long coil wire if i didnt like the look......
     
  23. 52Poncho
    Joined: Apr 23, 2011
    Posts: 256

    52Poncho
    Member

    Thanks Bubba
    Under the dash sounds like a great idea.
     
  24. Bubba: Thanks for the test. Very informative.

    Another question: For a non-typical application, assuming neither fits,
    which is better, the Ford Duraspark pick up, or the GM HEI pick up ???
     
  25. GMC BUBBA
    Joined: Jun 15, 2006
    Posts: 3,344

    GMC BUBBA
    Member

    Actually two different designs , the Ford has the stronger signal ( MSD Nascar etc) uses a single point with large magnet etc.
    The HEI is a split multipoint arrangement allowing a very crisp signal.
    The Chrysler offers another offering with magnet and wire coil as well.

    There are reasons for each i guess. We use the chrysler pickup...
     
  26. gotmark73
    Joined: May 14, 2008
    Posts: 144

    gotmark73
    Member

    So I can use the ugly s-10 coil to get the engine running. Which term is positive and which is negative? And what years were these used?
     

  27. Which is the most compact pick up/reluctor combo?
    Assuming the module is mounted externally.
     
  28. GMC BUBBA
    Joined: Jun 15, 2006
    Posts: 3,344

    GMC BUBBA
    Member

    The Chrysler is the smallest, that's what we use for our small base heis but good parts are hard to find etc
    .
     
  29. 52Poncho
    Joined: Apr 23, 2011
    Posts: 256

    52Poncho
    Member

    [​IMG]
    Photo courtesy of Chevythunder.com

    The remote coil has two connectors. The gray connector is the 12V coil power supply, the large pink wire goes to ignition "on" power for the distributor, the white wire can be hooked to a tachometer. The black connector has the smaller pink and white wires which goes to the two wire connector on the ignition module on the distributor. From black connector small pink to "B" and white to "C" on module.

    These coils are found on HEI engines with small caps (except inline 6's with large cap HEI with coil post), late 80's to 90's 350's, 4.3's and 2.5's mainly GMC and Chev trucks and vans. 2000 and up coils are usually 0.2 ohm primary and should work also.
     
  30. gotmark73
    Joined: May 14, 2008
    Posts: 144

    gotmark73
    Member

    Poncho, thank you for the explanation on the coil. My hope is to get the car running cheaply and then have Bubba build me an dizzy for the 2.3 motor that is low enough profile to not interfear with the intake I want to build. My "cheap" project is getting a little spendy and I am trying to save where I can so I can pay for the things I have no idea how to build, like a low profile Ford electronic ignition.
     

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