cheap POS aftermarket HEI modules

Discussion in 'The BS Topic' started by ULTM8Z, Sep 20, 2020.

  1. ULTM8Z

    ULTM8Z Veteran Member

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    Is there really any truth to this business about "matching" the HEI module to the coil? I'm certainly no expert on these things, but I don't know what the mechanism is for one module's performance vs the ignition coil vs another module...

    That's what actually prompted me in the first place to try the Dynamod that I had in my parts bin...
     
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  2. muscl car

    muscl car Veteran Member Lifetime Gold Member

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    Yes the MSD " street fire " parts are not good
     
  3. kenny77

    kenny77 Veteran Member Lifetime Gold Member

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    I've always replace both in matching sets......with Accel, no problems
    https://fordsix.com/archive/www.classicinlines.com/HEIdizzy.html
    This is an important factor since all the ignition companies we spoke to stressed the idea of properly matching the coil and module. The best way to do this is to use the coil specified by the manufacturer for its specific module. For example, ACCEL offers a stock replacement and two different performance modules for the typical four-pin HEI. Each requires its own coil to create optimal ignition power. What this means is that you should not mix and match coils and modules. In one particular situation, we combined a stock replacement module with a Petronix coil and the engine just seemed to run flat—as if the ignition timing were retarded, even though it wasn’t. As soon as we replaced the stock module with the matched Petronix module, the engine instantly responded and was again crisp and fun to drive.
     
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  4. ULTM8Z

    ULTM8Z Veteran Member

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    Yeah, there was an article I saw in SuperChevy.com with the exact same paragraph. They also said they tried to repeat that finding with testing other combinations of modules and coils but couldn't repeat it. Makes me wonder if that one situation was a fluke and they ended up with a bad module somehow. We all know the reputation of these "stock replacement" modules... lol.
     
  5. Todd80Z28

    Todd80Z28 Moderator Staff Member Lifetime Gold Member

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    I suppose theoretically the module could affect coil saturation, some of these aftermarket coils run higher than normal voltages, so I guess I could see it?? My stock stuff ended up working better than the MSD coil and module I had eons ago. The Skip White piece came fully loaded, it seems fine too. I'm sure my 9:1 350 at 1500rpm isn't exactly taxing it.:)
     
  6. GoldenOne7710

    GoldenOne7710 Equal Opportunity Offender Lifetime Gold Member

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    Bought a brand new Mallory HEI distributor about 17 years ago. It died on my maiden voyage when I built this engine. It wasn't the module that failed, but the magnetic pickup. Sucks to leave out with a brand new powerplant under the hood...only to return on a rollback tow truck.

    Mallory sent out a new magnetic pickup, but I couldn't trust it. Put in a Delco HEI distributor I had on the shelf, but swapped in a Accel coil and Pertronix Flame-Thrower module.
     
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  7. kenny77

    kenny77 Veteran Member Lifetime Gold Member

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    I bought a GMPP HEI for the engine I have now. That coil took a dump like in 8 months. I bought an Accel cap, rotor, coil and module because I'm stupid like that. The GM module is in my center console box.
    The MSD stuff seems like it was the shizzle....back in the day

    About the Skip white HEI, In all the past years, never heard of them failing.
     
    Last edited: Sep 21, 2020
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  8. QUAKE_WARS

    QUAKE_WARS Veteran Member

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    This is my fix all remedy. :)
     
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  9. Fbird

    Fbird Veteran Member Lifetime Gold Member

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    you can test the hei module at home with a digital multi meter. Will need to be on the car in order to test and its about 15 STEPS. Recall having to do this 1 time about 35 yrs ago (worked at a gas station) ...guys car would NOT run after I pressure washed the engine. Had to drill down to the EXACT problem to PROVE it was NOT the wash that killed the car....simple electronic failure.
     
  10. tom3

    tom3 Veteran Member

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    Oh my, the old "you musta done somthin" deal.
     

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