Msd 8973

Discussion in 'PSI Superchargers Tech Questions' started by Bob69, Nov 17, 2009.

  1. Bob69

    Bob69 Member

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    I think I just learnt the hard way the 8973 doesnt like to have any start retard programed in.
    Engine wouldnt make any spark, remove start retard function spark appeared. Any one had similar experience? Why doesnt MSD tell us this, why bother putting this function in if it doesnt work with 44 mag.
     
    #1
    Bob69, Nov 17, 2009
  2. Mike Canter

    Mike Canter Top Dragster
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    I guess this subject has been covered sveral times on this board. What you say is correct that the if the 8973 Start Retard function is used it will not let the car start. This is normal. The 8973 used to come from MSD with 10* retard in it and when first installed it would not start. The reason is that with the retard the rotor phasing is moved just enough that the weak spark during the start will not jump the gap between the rotor and the cap.

    Congratul;ations on figuring out what the problem was.
     
    #2
    Mike Canter, Nov 17, 2009
  3. Scouder

    Scouder New Member

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    Insert Will Hanna 8973 slam <here>. :D

    Sorry, couldn't resist!

    The 8973 seems to have some "personality", but I'm going to put one on anyway. The start retard, and stupid naming like "launch curve" and "run curve" are more than offset by the consolidation of features it offers. I was concerned at first, but info from people like Mr. Canter and others has clarified some of the mystery for me. On top of that, on my rig it would eliminate the need for the retard box, 6-shooter box, timer box, tach converter box, and rpm activated switch box. It appeals to me for the simple reason of all the real estate it frees up.

    -Scouder
     
    #3
    Scouder, Nov 17, 2009
  4. KennyKeller

    KennyKeller New Member

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    I've run one for 2 years with no problem at all. The start retard did get us in the beginning though.:rolleyes::rolleyes:
     
    #4
    KennyKeller, Nov 17, 2009
  5. Bob69

    Bob69 Member

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    Thanks guys.
    When diagnoising the problem, the rotor phasing wasnt the problem, I had a leed hooked straight up to the coil with a MSD test plug installed. No spark, so it wasnt a phasing problem. The 8973 just didnt allow spark. As soon as I removed start retard spark appeared.

    Has any got a function test method without starting motor, so I can check launch light shift light test etc
     
    #5
    Bob69, Nov 18, 2009
  6. isracing

    isracing New Member

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    (raising hand)

    I had the same issue, they should put a big neon green tag in the box saying DON'T ENABLE START RETARD YOU RETARD!

    Took me calling up and talking to ProMag before I got it working.

    I do wish that the guys on the ProMag line told me that the 7531 would work also, I always thought promag stuff only works with the promag. The 7531 does everything the 8973 does and more... After I told him what I'm doing after I bought it he said "Oh we usually recomend 8973 for FC's and Dragsters, and 7531's for Door Cars... sorry"
     
    #6
    isracing, Nov 24, 2009

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