HEI ground wire?

Discussion in 'Electrical Systems' started by bourbon_scotch, Jan 31, 2017.

  1. bourbon_scotch

    bourbon_scotch Veteran Member Lifetime Gold Member

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  2. Gary S

    Gary S Administrator Lifetime Gold Member

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    My feeling is that it is a bit anal to think you can out-engineer the engineers who designed this stuff and it works flawlessly for 40-50 years. Time can be better spent doing other things like having lunch.
     
  3. Hey G

    Hey G Veteran Member

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  4. APEowner

    APEowner Veteran Member

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    As an engineer I appreciate that sentiment. In this case of the linked reference in the OPs post however, we're talking about a combination of modified parts that could cause a problem.

    In that system as it was original designed the ground through the distributor body through the intake is fine. In a lot of original applications there's a ground wire tied to either the intake or the alternator bracket that's bolted to the intake that ensures a good ground.

    When you start looking at aftermarket parts, paints, anodizing and powder coating on parts that didn't have coatings originally and different engine grounding schemes it's easy to end up with un-grounded or poorly grounded parts. The electric choke heater on some carbs is another item that sometimes ends up not working due to an overlooked need for a ground.
     
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  5. tom3

    tom3 Veteran Member

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    Sometimes in electronics too many grounding points can do a lot more damage than solve problems. Ground looping, reverse currents etc. Wouldn't hurt to put a ground wire from the dist. to a cleaned spot on the intake, not to the firewall.
     
  6. Hey G

    Hey G Veteran Member

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    Why not the firewall?
     
  7. Fbird

    Fbird Veteran Member Lifetime Gold Member

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    if that is the ONLY ground from your engine to the body...your STARTER will be trying to use that little 12 ga wire as ITS ground while it uses 200+ amps to crank the engine = BAD
    Same way we "weld" our shifter cables .... bad engine ground. Adding ground wires is NOT a bad thing ; however, it would be more prudent to ensure each system is complete and seperate. We all know you really don't want to ground your radio to the engine.. same holds true for some other circuits as well.
     
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  8. larrylarry

    larrylarry Veteran Member

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    When I had my HEI out I drilled a small hole in the aluminum base an used a 1/4 X 1/2 hex head an ran a ground wire to the firewall. The only grounding the dizzy gets is from the gear meshing on the cam. Even though that may be enough, grounding to the firewall won't hurt anything. The middle wire in the plug is for the coil only.
     
  9. Hey G

    Hey G Veteran Member

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    I see...thanks for that. I have mine grounded...engine to subframe, but now I think I need one subframe to body.
     
  10. Fbird

    Fbird Veteran Member Lifetime Gold Member

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    i disagree with larrylarry... the module is grounded per its case. 1 of the 2 screws has a brass/metal contact the prevents you from crushing the module.... this screws into the dist housing.... therefoer the connectivity of said system becomes grounded via the dist. hold down clamp (and drive gear). which is grounded to the subframe AND teh firewall. NOW... the coil has a wire from one of its mounting screws that goes to the center of the dist PLUG IN. THIS be grounded somewhere.... (usually firewall) otherwise the coil will NOT energize. NOTE: do NOT ground the module to the coil!! MSD states "this will cause SEVERE interference in the module" ..
     

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