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Technical Flathead wiring

Discussion in 'Traditional Hot Rods' started by nosdan, Mar 31, 2014.

  1. nosdan
    Joined: Mar 27, 2009
    Posts: 228

    nosdan
    Member

    Here is a drawing of the wiring I have setup to test fire a 52 flathead with a new 12v internally resisted coil. I'm not getting any spark to the plugs, but the engine cranks over fine. New rotor, cap, wires and plugs. Could it be the points? Is my wiring correct? ImageUploadedByH.A.M.B.1396319303.819111.jpg

    Thanks


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  2. gillman
    Joined: Apr 16, 2005
    Posts: 12

    gillman
    Member
    from n.j.

    Remove the ground wire from the neg on the coil.You should only have the wire from the distributor on the neg side.
     
  3. hanginlow58
    Joined: Sep 16, 2003
    Posts: 364

    hanginlow58
    Member

    pretty sure that ground wire going to the coil is your problem, try it without it.
     
  4. brokenspoke
    Joined: Jul 26, 2005
    Posts: 2,874

    brokenspoke
    Member

    Your grounding the coil
     
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  5. Tudorp
    Joined: Mar 27, 2014
    Posts: 174

    Tudorp
    Member

    What they said. Your coil is shorted directly to ground causing it to discharge into ground and not through your points for a spark.
     
  6. Like they said, remove ground wire at coil. I wonder how hot that coil got?


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  7. Should there also be a relay in the mix?
     
  8. Bruce Lancaster
    Joined: Oct 9, 2001
    Posts: 21,648

    Bruce Lancaster
    ALLIANCE MEMBER

    To elaborate a bit...the wire from coil to the points IS the ground system, grounding through the points to charge the coil, then firing the coil when the ground is removed by the points opening...so, with that terminal grounded by a wire into main circuit, points don't do anything at all and since ground is always there, your coil cannot fire.
    Gratuitous extra info: Sounds like you have the original distributor...it has two electrical problem areas that need to be examined because they are nearly invisible. One is a little ground strap from point plate to body of distributor...this eventually will break from normal flexing, leaving you with erratic ground and poor performance.
    The other place to watch is the small wire from coil...it goes through a plastic bushing where it enters the distributor, and this is a failure point when that bushing disintegrates.
     
  9. nosdan
    Joined: Mar 27, 2009
    Posts: 228

    nosdan
    Member

    Great Thanks for the insight... knew it had to be something stupidly simple. I'll check the other items there Bruce! Thanks for the tips.
     
  10. Tudorp
    Joined: Mar 27, 2014
    Posts: 174

    Tudorp
    Member

    All of what he said.. ;)

     
  11. Flatheadguy
    Joined: Dec 2, 2008
    Posts: 2,037

    Flatheadguy
    Member

    No relay. No way. Why would you want one in this circuit?
     
  12. Tudorp
    Joined: Mar 27, 2014
    Posts: 174

    Tudorp
    Member

    No relay in a coil circuit. Like mentioned above, all it is, is charging a coil, grounded through points, then discharging that coil through opening those points suddenly breaking that ground which causes a spark & discharge of the charged coil. No complicated circuit with relays etc. Those are generally in control type circuits.
     
  13. Mr48chev
    Joined: Dec 28, 2007
    Posts: 24,980

    Mr48chev
    ALLIANCE MEMBER

     

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