8973 mag comp

Discussion in 'PSI Superchargers Tech Questions' started by blownapex, Oct 22, 2011.

  1. blownapex

    blownapex Member

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    we ran some 3.80s outlaw promod and our mph is down
    the timing starts and is set at 24 degrees
    after it ramps out and back in it only goes
    back to 22 degrees
    what is the mag compensation all about
    i have it set on 2 degree as it should be for
    a crank trigger
    but the instructions say pro mag should use auto setting
    what about promag and crank trigger
    is their some kind of varying timing with rpm going on
    im looking at it on race pak v300 with lahee timing module
    if you set the timing on crank trigger and then set it on mag
    shouldnt this be what the timing is
    unless timing changes a little with rpm (confused about this)
    thanks
    duane
     
    #1
    blownapex, Oct 22, 2011
  2. JustinatAce

    JustinatAce Member

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    Have you tried writing a brand new timing curve from scratch on the 8973? It's very easy to compound timing retards. If the car can idle @ 24 degrees with the box on, then something extra was written in to the timing map..
     
    #2
    JustinatAce, Oct 23, 2011
  3. Mike Canter

    Mike Canter Top Dragster
    Staff Member

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    Lets see if I can answer your questions. Yes the mag comp should be left in auto with the Pro Mag and with a Pro mag with a crank trigger. Don't complicate your life by ever changing it. Set it in Auto and time your car. Other than Auto is for non MSD systems.

    Witha ProMag your timing should not change with RPM unless you command it to change. This is not so with non ProMag that will retard when under load. Having said that t is possible for timing to jump around with RPM if your mag drive is worn and you do NOT have a crank trigger. With a crank trigger it will be rock solid and that is the reason one uses ancrank trigger.

    Not sure I understand the question about setting the timing on the crank trigger and then on he mag. If you are using a crank trigger then the position of the pickup is what is controlling your timing and NOT the mag. Changing the mag psoition when used with a crank trigger only changes your rotor phasing. You may need to reword that question to help me understand it.

    The other thing that confuses me is the using the 8973 and talking about a Leahy timing control. Ae you talking about the Leahy ignition timing record module for the Racepak. If so then I do see a little movement of the ignition timing with RPM and that is probably due to crankshaft flex.
     
    #3
    Mike Canter, Oct 23, 2011
  4. blownapex

    blownapex Member

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    8973

    thanks mike
    the lahee is for recording timing into racepak
    and i set crank trigger first to 24 then i set
    mag(phasing) to 22
    both with a timing light
    ive been running it on 2 degree mag comp
    instead of auto
    will this retard 2 degree going down track then when i let off
    and the rpm comes down it slowly tapers up to 24 at 10 seconds
    thanks
     
    #4
    blownapex, Oct 23, 2011
  5. Mike Canter

    Mike Canter Top Dragster
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    In your setup I always set the timing just on the mag at 24* then attach the crank trigger and set it for 24* now all is right in phase. The Electronic Points Box for the ProMag systems has auto compensation to take care of the "mag effect" which I have explained in the past. Not sure what running it in Manual 2* will do because I have always put it in Auto and forgot about it. It does seem logical that it might change the timing when in manual. Since you can record your timing then switch it to Auto and compare it. I would be interested in hearing from you on any difference noted.
     
    #5
    Mike Canter, Oct 23, 2011

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