Msd 8973 Help

Discussion in 'PSI Superchargers Tech Questions' started by H BROWN, Nov 26, 2008.

  1. H BROWN

    H BROWN blown alky

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    I am going to try the 8973 to help control timing in a converter car. I have tried to read all the post in archieves and if I read right the major problem is shielding and grounding the crank trigger. I assume I need the Leahy trigger also.
    I have the RCD front cover with the titanium crank support bearing in a hemi. What leahy trigger do I need and will I need a special mt? I currently am ol school with only a mag 44 and pts box.
    The next question is I want to mount the 8973 in the passenger side like maybe the door x bar. I have a ACD shift box,starter solenoid,fuse panel,and main battery supply cable on a panel mt on the front dash bar. A RPM computer on the floor like where the pass seat goes. Will there be a electrical interference with all this electronics in this area or is it just from the mag 44 generator?
    Another problem is the plug in that goes to the point box is to short. I need maybe 6 more feet, can I get an extension, or do I need to move points box in car and get an extension from the mag 44? My coil and pts box is currently mounted under the mag on the frame rail. Coil wire is about 12inches long. If I mt 8973 close enough to plug in the 8 inch plug to the points box, I am worried about this EMI interference.
    Any help is appreciated to avoid this fear of random cyl timing problems and tearing up parts.
    Hopefully I can get the computer set up programing right so I dont have random timing issues. I have just enough skills to sucessfully lock my up my lap top:D.
    thank for all help Howard
     
    #1
    Last edited: Nov 26, 2008
    H BROWN, Nov 26, 2008
  2. Mike Canter

    Mike Canter Top Dragster
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    Howard, the Leahy pickup works just fine as does the MSD pickup with the armored cable. We have never had a problem with the MSD pickup. You can get the mounts from RCD for both types.

    As far as mounting it is highly recommended that you mount the data logger away from the 8973 just in case. The 8973 is not an ignition box like a Digital 7 and does not put out any high amplitude trigger like a capacitive discharge ignition system it is just a control box but it is still recommended to keep the logger as far away as possible. All you can do at this point is to just try it and see if the logger works OK. I don't think it will effect the 8973. The only problem with a high noise spike maybe the ACD shift box when it shifts. I would use the MSD capacitor on the power input line to the 8973 just for added protection. I would also run a separate power line from the battery to the 8973 through that capacitor. Keep that crank trigger away from all other lines. Do not run it in a wire budle with other wires.

    When you say you need to extend the cable from the Point Box to the 8973 I am assuming you are talking about the rev limitor plug in the top of the Points Box. I made my own extension for that and I used a shielded cable. I don't know if I needed it or not but used it just in case and I grounded the shield to the chassis. I cut the two prong plug off the short cable and added it to the end of the extension and used heat shrink ito insulate the connections.

    We have never had a problem with our 8973 mounted inside the car.

    If you have questions or problems please feel free to email me direct.
     
    #2
    Mike Canter, Nov 26, 2008
  3. H BROWN

    H BROWN blown alky

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    Mike thanks for the reply and tips. I will be installing in a few days.
     
    #3
    H BROWN, Nov 27, 2008
  4. Kevin O'Dell

    Kevin O'Dell Member

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    For what it's worth I would recommend an ignition tester. We used it on our car and actually found and fixed several errors without starting the car. The tester thinks the car is running and you can see what the box is doing in each gear if you like. It helped us.
     
    #4
    Kevin O'Dell, Nov 27, 2008
  5. osolberg

    osolberg New Member

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    Tester for 8973

    Hi Kevin ! What tester would you use for the Promag 44 ? I have yet not seen one as most manufacturers tell me the generator inside the mag needs to spin to generate any spark. I would be very interested to buy one as we too are installing the 8973 controller this winter.
     
    #5
    osolberg, Nov 28, 2008
  6. Mike Canter

    Mike Canter Top Dragster
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    I use the Digital 7 ignition tester. It will not test the mag and the points box but will test the 8973. It emulates the crank trigger turning so it thinks the motor is running. You can test all the functions on the 8973 and view everything happening on a laptop. I have used it to locate many problems on systems. It is worth its weight in gold.
     
    #6
    Mike Canter, Nov 28, 2008
  7. racerb

    racerb New Member

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    We used the 8973 in a tafc with no problems. We have a msd shielded trigger with the RCD mts, we also use the msd Capacitor. Due to the time constraints when we installed it, we mounted the 8973 closed enough to not have to extend the rev limit wire. The box works great contrary to what you might hear. There are a lot of ways more ways to scew up your timing now so be carefull. I recomend purchasing the tester, its nice for double checking your programs, and the set up cap. Phasing is critical.
     
    #7
    racerb, Nov 28, 2008
  8. Will Hanna

    Will Hanna We put the 'inside' in Top Alcohol
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    8973

    howard-

    few things you need to do with the 8973. my first recommendation is to send it back and try to get your money back before it goes skitzo, but it looks like you're going to use it. so...

    get the shogun diode kit for transbrake solenoids. the high voltage will feed back and mess the box up, namely delay when the box lets the two step go and starts the run timing curve.

    go with the leahy trigger. period.

    the software isn't clear on this, but we learned that 0.0 seconds on the retard curve is how much timing you have retarded on the button. so if you want 5 degrees out on the button, drag the dot down to 5 degrees on 0.0 seconds then do with it what you like from there. in other words, there is no need to use the launch retard setting because it will throw a giant shitfit if they are both used.

    try to buy a long serial cable to go from the trailer to the box that way you aren't lugging the laptop around everywhere. that will significantly lower the life of your laptop.

    msd has it somewhere on their website the part number of the serial to usb adaptor they recommend....unless you still have serial ports on your laptop.

    let me know if you ever need any more help.
     
    #8
    Will Hanna, Nov 30, 2008

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