Pro Mag 20 to 8973 w/o crank trigger connection...

Discussion in 'Manton Push Rods Top Alcohol Tech Questions' started by WJ Birmingham, May 19, 2008.

  1. WJ Birmingham

    WJ Birmingham New Member

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    I concur. I'll take the time and do it.

    On to the next step of things, since it's hooked up. Right now it's simply functioning as a tach output and rev limiter.

    Here's the manual: http://www.msdpromag.com/pdf/8973_frm25079.pdf

    As was already stated, I plan on using the violet/blue wire to fire the air shifter.

    My next question would be as to how the main reset Dark Blue wire works.


    "This is the main reset wire for several features of the Controller. When
    12 volts are applied to this wire it will activate the Launch Rev Limit. It
    will also activate the Launch Retard value and the Launch Curve.

    It will also reset the following programmable features:
    Shift Light Sequence will go to first gear.
    The Time Retard Curve timer will reset to 0.0 seconds.
    The Time Switch timer will reset to 0.0 seconds."


    I have my line lock/t-brake working via one momentary switch. I have a dual relay that I use to activate the t-brake. Turning on a switch on the panel powers the first relay, which then gives power to the second relay. The momentary button is then used to trigger the second relay to fire the t-brake.

    I would have to think that in a clutch car, a momentary switch would be hooked up to the clutch pedal, and when the clutch pedal is pressed, it resets the 8973 to first gear.

    I guess my question is this... If I hook up the Dark Blue wire to the line lock, it will see 12V continuous until I release the line lock. Does the 12V have to be disengaged before the 8973 will fire the 2nd/3rd gear shifts?

    I could hook it to the t-brake, but then that leaves me in the dark as to how the 8973 would know when to reset for the burnout.
     
    #41
  2. Mike Canter

    Mike Canter Top Dragster

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    That dark blue wire is what I call the "ready set go" wire. As you have stated. It does several things when 12 volts is applied. The 8973 comes on line when the power is applied or the car is started in the "Run Retard Curve" (lower great graph on the computer screen). When you apply 12 volts momentarialy to that dark blue wire it switches to the "Launch Retard Curve" (upper right side graph). This is important if you have two different timing curves. You need to apply 12 volts to the blue wire before you check your timing. The other thing that happens is that while 12 volts is applied to that blue wire the Two Step is activated. Also that resets your shift lights to the right order.

    The normal hookup for a clutch car is via the clutch switch so that 12 volts is applied while the clutch pedal is depressed so when you launch it starts everything from that point. For an automatic tranny with a transbrake then when the transbrake is applied. No relay required in most normal installations because not much cuurent draw on the blue wire.

    Here is a trick for you.....take one of the three retard wires, the pink, the dark brown or the tan and hardwire it to 12 volts so anytime the box is on you have 12 volts activating that one retard. Now use that retard as the same as a timing chip. First set it with 4 or 6 or whatever degrees in it then time your car and set the timing where you want it (with this retard always activated). Now when you check the timing at the track and you find it off a little bit or you want to change it then change the amount of retard by that amount. It makes adjusting the timing very fast and you don't have to keep turning the mag or moving the crank trigger:rolleyes:.
     
    #42
  3. Mike Canter

    Mike Canter Top Dragster

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    Forgot to ask. Are you going to use the burnout limiter? Then if so you need a separate switch such as a momentary pushbutton on the steering wheel or gear shift. Since you don't keep the line lock on during the whole burnout you don't want it hooked to that.
     
    #43
  4. WJ Birmingham

    WJ Birmingham New Member

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    Mike;

    No plans on using the burnout limiter as of current. I guess, however, that I could hook a toggle switch up to that wire specifically for burnout. Would suck, however, to forget to turn it off, lol.

    Over the years I've gotten really good with my right foot. Managed to not over rev the last motor, using a Super Mag 3 with no limiter at all.

    Is there a means of electrically creating a single 'pulse' to the dark blue wire when I activate the line lock?

    This would allow the auto reset of the dark blue wire each time the line lock is fired. I use the line lock for burnouts as well as keeping any movement at all from occuring while on the t-brake.
     
    #44
  5. Mike Canter

    Mike Canter Top Dragster

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    You don't have a clutch switch? Yes, you can use the line lock if you are not using the Two Step. If you use the Line Lock the Two Step will activate during the burn out while the line lock is activated
     
    #45
  6. WJ Birmingham

    WJ Birmingham New Member

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    Actually...

    If I had a pulse on the line lock side, it would simply reset the timers/shift stuff.

    If I hooked up full 12V once the t-brake is active, the 2-step would work just fine.

    Again, I think this can be done if I can figure out how to simply pulse the Dark Blue wire when I press the line lock button.
     
    #46
  7. Mike Canter

    Mike Canter Top Dragster

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    I don't understand "pulse". Why do you want to pulse the blue wire?:confused:
     
    #47
  8. Bottlefed

    Bottlefed New to Blowers

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    Pulling timing with pink, dark brown, tan

    Mike,

    I have used this trick (pulling 5 with the pink) on nitrous motors in the past to change base timing with the digital seven.

    However on these motors I was pulling 15 with the cranking retard so the extra 5 that was in the motor during during cranking was more than offset by the 15 being pulled. It seems that since you can not use the cranking retard that you would not want to put another 5 on the base timing that will not be removed untill you exceed the 800 rpm or whatever minimum rpm you set the the 8973 at. In addition you would be adding 5 degrees of rotor misalignment to whatever amount you are pulling with the 8973 during the run. Maybe I am missing something.

    Another trick I used in 10.5 with the early boxs without slew rate was to mount a button on the wheel and use it to pull a preset amount of timing usually around 5 whenever I detected wheel spin during a run, this way the nitrous would not be turned off by the full throttle switch like it would if you lifted.
     
    #48
  9. Mike Canter

    Mike Canter Top Dragster

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    Good point and you are not missing anything. It must be that the few degrees that are used in the one Step Retard used as a Run Chip are not as much as the default 10* Start Retard.
     
    #49
  10. WJ Birmingham

    WJ Birmingham New Member

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    Ok, let me explain the way it's wired...

    From fused 10A to momentary switch on shifter.

    Momentary switch splits off to line lock and t-brake.

    Line lock is hot with the button all the time.

    T-brake is only hot when powered from switch on panel.

    I want the single 12V 'pulse' on the line lock to trip the reset circuit on the dark blue wire.

    I want continuous 12V when the t-brake is active to reset the box and activate the 2-step.

    That make it a bit more clear?

    Yes, I could skip the line lock 'pulse' and simply put a reset button on the dash. But, that adds just another thing to remember in the staging process. I prefer as much automation as I can get.
     
    #50
  11. Mike Canter

    Mike Canter Top Dragster

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    And the purpose of the 12v reset to the 8973 on the line lock is? All you would have to remember is after you start the car just hit the transbrake button once before you move. It would be OK to do the burnout without a reset on the 8973.
     
    #51
  12. WJ Birmingham

    WJ Birmingham New Member

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    And if I'm not driving? Then I have to remember to tell the driver to hit it. I want it automated.

    I found what I need: http://www.airotronics.com/site/product-singleshot_TH3P.php

    Waiting on pricing now.
     
    #52
  13. Mike Canter

    Mike Canter Top Dragster

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    You are getting too complicated. It doesn't make any difference if the 12 volts is applied to the blue wire for 1 second, 5 seconds or a minute. All you need is to wire it up to the transbrake switch so when the transbrake is applied it sends 12 volts to the blue wire. You don't need it from the line lock. The transbrake application and release on the launch will do everything for ya
     
    #53

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