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

Discussion in 'PSI Superchargers Tech Questions' started by WJ Birmingham, May 19, 2008.

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  1. pete9857

    pete9857 Member

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    wrap

    It's a piece of heat wrap sheath that's used on plumbing or wiring when routing close to exhaust systems. About 1/2 inch i.d.. I'll see if my son can snap a couple for you.
     
    #21
    pete9857, May 20, 2008
  2. pete9857

    pete9857 Member

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    grounds

    We also have a ground wire running from the battery to the block, then to heads, then to the frame where all the grounds meet.
     
    #22
    pete9857, May 20, 2008
  3. Will Hanna

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

    Pete:

    I'm not an electronics guy; I have a business degree and look at the bottom line and end result. I can't tell you why these boxes are throwing fits, but they are, and when they do, it's not like an 'oh gee whiz we nipped a piston' deal, its a real deal kick some rods out problem. Then pretty smart people like Marty Thacker, Mick Snyder, Ken Perry and others un plug it, and instantly quit having problems. I know Thacker and Snyder went through more than one motor and worked with MSD during the problem.

    This is just a general statement to a lot of people that get on here, but sometimes you need to listen to some of the veterans on here instead of just what you want to hear.

    I'm going to start an 8973 thread....so this doesn't get hijacked further.
     
    #23
    Will Hanna, May 20, 2008
  4. racer313g

    racer313g New Member

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    Will,

    Feel free to move this to the 8973 thread if you wish but I have a couple of questions for you or the veterans.

    How did anyone narrow down issues specifically to the 8973? What kind of issues were consistently happening that lead them to the 8973 instead of anything else? As stated, we've run one for 5 years without any issues. You'd think that if they had mysterious problems they would have crept up over that time. I read/hear people bashing the 8973 but what evidence has been presented to prove that the ignition box is/was the problem?

    Thanks
     
    #24
    racer313g, May 20, 2008
  5. pete9857

    pete9857 Member

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    8973

    Will, I hear ya. We did have one issue and imediately took the box off the car and headed to the MSD trailer. I watch them check it, answered a few questions, then took it back to the pits and found a disconnected wire in the harness. I also fell victim to the ( box is the problem) lynch mob. I not saying there, Marty, Snyder,etc, boxes weren't junk, but there is alot going on in them. My son is the computer guru and I have the Automotive knowledge, 36yrs. I tell him what I want to happen on track and he programs the box and we watch it happen on the laptop. He drives the car and knows what is supposed to happen on the run. One wrong stroke of the keyboard can spell disaster.

    Thanks for listening to my babbleing.
     
    #25
    pete9857, May 20, 2008
  6. Will Hanna

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

    Due to the cost to run an alky car, sometimes racers just don't get a chance to diagnose a problem. Particularly in the instance if ignition components. While when other ignition components fail, USUALLY, the worst case scenario is you lose a run or lose a round. However, in the case of the 8973, the worst case is disasterous.

    When racing at a competitive level, at the first hint of an ignition problem, you usually replace points box first, and usually the coil at the same time. Coil failure is less common than points box failure. You just don't have money or time to make small changes, change a ground, change a coil wire, or in the case of the 8973, make a setting change. On a Top Alky car, with cost per run approaching 2000 or more, you just can't afford to make another wasted run if you have spares on hand to change at the track, then send out to get tested after the event.

    If a racer at any level starts killing motors, unplugs that box, and quits killing motors, you're going to have a hard time convincing them to plug it back in and have a go at figuring out the problem.

    To compound the problem when you have racers like Thacker (2x Div. 3 Champ), Snyder (3x Div. 3 Champ), Perry (Quickest Blown Car ever) having major problems with the box, their accomplishments should be a testament to their attention to detail regarding the boxes. All of these racers have said that MSD told them the box wasn't the problem. I tried to talk straightforward with them about it several times in the trailer, and they looked at me like I was the village idiot. (I know I'm leaving the door open there).

    SO is it the racers responibility to diagnose and find the problem with the 8973 and take the chance of blowing another motor up? SO what if MSD offers another box for free. You're talking about a free 700 dollar box in exchange for $10k in damage. That's why usually racers don't plug the box back in, and maybe that's why you don't see a detailed analysis published.

    I really liked some of the features of the box. I wanted it to work just like many of you want to "hear" that it's ok to run. Use at your own risk. Just know that if that box goes bad, it's not going to be pretty.
     
    #26
    Will Hanna, May 20, 2008
  7. Mike Canter

    Mike Canter Top Dragster
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    The software and electronics used in the 8973 originate from a tried and proven Digital 7 Ignition system which has been in use outside the blower world for almost ten years that I know of without problems. I have been using Digital 7 systems that long also. The only real problem that I know that can still happens with both the analog and digital MSD ignitions is the false triggering from the crank trigger by electromagnetic interference picked up by the older type unshielded trigger cables.

    When the Digital 7 systems were first introduced there where all kinds of stories how they messed up motors. They were blamed for everything as is now the 8973 by a few.

    We have to also look at how many other MSD 8973 systems are being used on blower cars both in alky funny cars and in blown ProMods without any problem. The 8973 cannot just go out there and make random processor changes. It doesn't have a mind of its own.
     
    #27
    Mike Canter, May 20, 2008
  8. WJ Birmingham

    WJ Birmingham New Member

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    Mike;

    Finished wiring up the box tonight, with all associated grounds and the big arse capacitor from MSD.

    Tried to fire the motor and nothing. Unplugged the box and plugged the mag back in and it fired just fine.

    Started to check my wiring when I remembered you saying that the start retard would keep it from firing. Sure enough, it was set to retard 5 degrees on start. Changed it to off and bam, the motor fired right up.
     
    #28
    WJ Birmingham, May 20, 2008
  9. Eric David Bru

    Eric David Bru Member

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    WJ,

    You will also want to ground the PN 8973 to the battery.

    EDB
     
    #29
    Eric David Bru, May 20, 2008
  10. WJ Birmingham

    WJ Birmingham New Member

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    Doesn't show anything in there about a direct battery ground. Ran the ground from the 8973 to the capacitor, then back up to the points box, as shown in the wiring diagram. The battery is grounded very well to the frame rail.
     
    #30
    WJ Birmingham, May 20, 2008
  11. Eric David Bru

    Eric David Bru Member

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    You might want to discuss it with a Senior Tech at MSD then.

    EDB

    ...I could be misinformed.
     
    #31
    Eric David Bru, May 20, 2008
  12. aj481x

    aj481x Member

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    For whatever it's worth, we have used the same 8973 for 2 years without any problems.
     
    #32
    aj481x, May 21, 2008
  13. Flyboy68

    Flyboy68 Member

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    I plan on using the Digital 7 7531 w/ our Promag 44 instead of the 8973. Doesn't both boxes work pretty much the same? What features does the 8973 have over the Digital 7???
     
    #33
    Flyboy68, May 21, 2008
  14. pete9857

    pete9857 Member

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    WJ, the frame doesn't provide a good current path. Run a ground from battery to your intersect point on frame, thus eliminating the frame as a ground path all together.
     
    #34
    pete9857, May 21, 2008
  15. WJ Birmingham

    WJ Birmingham New Member

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    Here comes a 30' foot lead... Sigh...
     
    #35
    WJ Birmingham, May 21, 2008
  16. 572ALKYKB

    572ALKYKB New Member

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    Chrome Moly Grounding a no no

    Pete9857
    I was going to post the same thing !
    The reason is chrome moly is a terrible conductor.
    The integrity of chrome moly is too hard.
    The harder the metal the more resistance there is.
    That is one reason gold and copper are good conductors
    because they are soft metals.
    What we do is run a copper ground cable from the battery to a terminal strip and distribute all the grounds from there. Our chassis has no grounds hooked to it at all. (Just my 2 cents)
     
    #36
    572ALKYKB, May 21, 2008
  17. td314b

    td314b New Member

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    Glen

    HAHA U must be a lot smarter then me :) of course that was a blatant statement of the obvious. No 8973 for me. Like everything in racing...each racer has to find their own way. What works for one guy may not work for another. If you can use the 8973 and it doesn't destroy your motor then Kudos!

    I will stay away from it..In truth my electrimotion timer box can do my fuel and my timing more then adequate and it is so simple to use. That works for me so it stays on the car.

    Sorry Glenn...not going to hurt my stuff because of a box...BTW I have 2 of them in the shop...if ya want a spare let me know! LOL :) they are expensive paper weights right now.

    Troy
     
    #37
    td314b, May 21, 2008
  18. fastavenger 588

    fastavenger 588 New Member

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    hay td314b are the boxes new or used send me a private message:)
     
    #38
    fastavenger 588, May 21, 2008
  19. WJ Birmingham

    WJ Birmingham New Member

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    My chassis isn't moly... It's mild steel. I'm limited to a 7.50 cert.
     
    #39
    WJ Birmingham, May 21, 2008
  20. pete9857

    pete9857 Member

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    grounds

    Still, if you run seperate grounds, then your not chasing your tail at the track wondering why weird things are happening.
     
    #40
    pete9857, May 22, 2008
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