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Changing ignition advance on a 3.2 qv

Discussion in 'Technical Q&A' started by snj5, Sep 20, 2004.

  1. snj5

    snj5 F1 World Champ

    Feb 22, 2003
    10,213
    San Antonio
    Full Name:
    Russ Turner
    Will be dynoing the car and playing with the distributor advance (mine is converted with a Mallory distributor, MSD and a Norwood adapter) this Saturday in San Antonio. All of my previous dynos were run with an idle advance of 11 and a max advance of 31 at 3500 rpm (a little less than stock at higher throttle settings). Max airbox cover off figure was 238 rwhp or close to 290 at the flywheel (on stock FI cams!) Will roll in 2 degrees at a time to see what happens, but will max at 36 - 37. Will dyno after each change.

    I know the qv's don't like as much advance as the 2v's (i.e. 40+) - any experience on this? I also am still running the stock plug gaps and have learned that I should open them up a bit with the MSD - other suggestions?

    Will post results
    Many thanks
    rt
     
  2. snj5

    snj5 F1 World Champ

    Feb 22, 2003
    10,213
    San Antonio
    Full Name:
    Russ Turner
    Road report
    Dyno appt. is not for 3 more days, but took it out on a short road test with idle advance at 14 advancing to 35 at 3500; Starts well and ran fine, no odd pinging or anything. Seemed pretty perky to me with great rip in response to dumping the throttle, but did not get much over 5500 rpm. Filled up with Techron Supreme in preparation.
    Hopefully numbers this weekend, but she is tolerating the advance increase well so far...

    I guess this thread is of remarkably little applicable interest except to the Electromotive Ign and EFI qv guys that can vary their advance, but will keep the numbers coming for posterity.

    DIY maintenence notes:
    For those of you who don't have one of those adjustable advance multi function timimg lights, they are great! The single distributor on the aft bank makes adjustments quite easy, but the key to the whole show for my failing eyesight is painting the TDC timing marks white.

    best
    rt
     
  3. mk e

    mk e F1 World Champ

    Oct 31, 2003
    11,505
    The twilight zone
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    The Butcher
    Russ, for what it's worth, Here is my ignition map (at 0 psi), but I didn't really get to optimize it yet.
    RPM-degrees
    0 - 8
    500-10
    1000-16
    1500-20
    2000-25
    2500-28
    3000-30
    3500-30
    4000-31
    4500-32
    5000-32
    .
    .
    .
    7700-32
     
  4. snj5

    snj5 F1 World Champ

    Feb 22, 2003
    10,213
    San Antonio
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    Russ Turner
    Mark - thanks
    4 valve?
     
  5. pma1010

    pma1010 F1 Rookie

    Jul 21, 2002
    2,559
    Chicago
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    Philip
    Russ
    Awaiting your results with interest.

    One "data point" to think about (and all engines are different). On the 4-valve/cyl, 9.5:1 CR Mazda Miata engine, we found it easy to load in too much advance, to the detriment of power. Indeed, the "advance until it pings and then back off 2 - 3 degrees" adage did not work for NA cars.

    BTW, max power was at about 26 - 27 degrees BTDC.

    You might think about a testing regime where you base line, go up a couple of degrees with the curve, go down a couple to understand sensitivity to, and direction of, change.

    Philip
     
  6. Matt Morgan, "Kermit"

    Matt Morgan, "Kermit" Formula Junior

    Nov 12, 2003
    405
    Ferndale, WA
    Russ, there are those like us who are taking notes on evey bit of info we can get!
    I certainly agree, the 4V do not seem to benefit from as much advance as the 2V do.
    As is often the cas, Phillip is right on the money in his input.
    Some food for thought...
    The newer cars all have detonation sensors. I wonder how hard it would be to adapt just that part of their system to older cars? All it would really need to do is set off a dash light.
    Any input? I'd sure like to have one, if for no other reason than Dyno tuning, but in daily use, wouldn't it be handy?
    Kermit
     
  7. mk e

    mk e F1 World Champ

    Oct 31, 2003
    11,505
    The twilight zone
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    The Butcher
    yes, QV.

    To Phillips point, my buddy found on his H-D drag bike the correct timing was 22 degrees. +2 he lost 5%, -2 was 10%. My 0 psi timing is my best interpetation of the stock maps, but smoothed a bit to remove stuff that was clearly EPA driven. I kept the stock timing as the baseline figuring ferrari must have dynoed these things and should have gotten it about right. I will probably adjust my maps based on what you learn though.

    Mark
     
  8. pma1010

    pma1010 F1 Rookie

    Jul 21, 2002
    2,559
    Chicago
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    Philip
    One device that does this well is a J&S Knock Sensor. [BTDT with the Mazda 7 or 8 years ago]. Has a plug that bolts to the engine block (we used an engine mounting point, but anywhere where the sensor can "hear" the frequency well works. Gets wired into the ignition trigger (with the Mazda, we just intercepted the cam angle sensor). Has two modes: retard all cylinders or just the one experiencing the "ping". Pulls up to 6 degrees. Has a sensitivity control to govern how "loud" the input needs to be before it pulls timing.
     
  9. snj5

    snj5 F1 World Champ

    Feb 22, 2003
    10,213
    San Antonio
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    Russ Turner
    Dyno results

    3.2 qv, 9.2:1 compression
    15 degrees idle at 1000 rpm advancing to 35 degrees at 3500 rpm
    Carb settings 40 dcnf, 36mm, 140, f24, 190, 55

    Max power = 241.6 rwhp @ 6,700 ( ~ 294.6 flywheel)
    Max torque = 201.9 rwft-lbs@ 5,300 ( 246 flywheel)

    Not bad for stock cams.

    Thanks to MarkPDX and ShanB for moral support today!
     
  10. bill308

    bill308 Formula 3
    Silver Subscribed

    May 13, 2001
    1,080
    Windsor, CT
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    Bill Sebestyen
    Russ,

    Are you saying best HP was achieved at 35 BTDC? What did the fall off look like at +/- 2 degrees from 35 BTDC?

    How about a 2V, carb car? Anybody have a best HP vs toatal advance for these animals based upon dyno runs?
     
  11. snj5

    snj5 F1 World Champ

    Feb 22, 2003
    10,213
    San Antonio
    Full Name:
    Russ Turner
    Bill

    Same car, 31 BTDC max advance starting point yielded 236 - 238 hp.
    Power fell off pretty fast after 35/36 degrees advance, but ran into MSD problem so didn't pursue.

    2v cars require more advance than 4v cars.

    best
    rt
     
  12. pma1010

    pma1010 F1 Rookie

    Jul 21, 2002
    2,559
    Chicago
    Full Name:
    Philip
    Russ
    If I remember 4v curves right, this is a lot more advance than the "0" vacuuum (WOT) curve, isn't it?
    Philip
     

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