71 Duster Timing

Mopar Performance Issues

  1. slidey06

    slidey06 Member

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    I just finished installing a sniper EFI kit on my 71 Duster and the car is reluctant to start without giving it gas and stalls after idling for a few minutes or when I try to press the throttle too quickly. If I try to get on the gas without easing the pedal down it's like there's no gas for a second and then it shoots up a few thousand RPM, pops then stalls. I think this is probably a couple of issues including timing. The sniper tuning is new to me so I don't know what settings to really play with to get the car to drivable. If anyone could provide information on where I should start with timing or anything that may get the car running well, I'd greatly appreciate it. I have a couple data sets from the sniper that I can provide

    71 Duster 318
    340 heads
    edelbrock intake
    sniper EFI and full hyperspark ignition system
    street/strip cam
    timing at crank and idle- 15.6
    timing at WOT- 40

    EFI DATASET.jpg
     
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    • MOPAROFFICIAL

      MOPAROFFICIAL FABO Gold Member FABO Gold Member

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      Back the total timing from 40 to 34.

      If you need to run more initial...then you'll have to tailor the timing curve of the distributor...which is a good idea.
       
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      • GTX JOHN

        GTX JOHN FABO Gold Member FABO Gold Member

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        You can buy light springs
        We run vacuum advance to straight
        manifold rather than ported and that really helped
        my son's 340.
         
        Last edited: May 23, 2022
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        • Bewy

          Bewy Well-Known Member

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          15-16* BTDC is ok for idle timing. Not the problem. Sounds like a Sniper problem. Does the system use any sensors? I would check those first.
           
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          • Sr4440

            Sr4440 Active Member

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            Are you tuning with the handheld, or are you pulling the SD card and using a laptop?
            A few more questions
            Did you lock the timing and set the distributor at 15 degrees?
            Is your hot IAC setting between 2-10%
            Looking at your log, your idle A/f is 13.8, but when you accelerate it commanding 14.0? The accel enrichment adds fuel, then pulls it away. Something looks wrong
            If you have any question, you can look up my number at www.cen-texenginedyno.com and give me a call, I will walk you through any issues you're having.

            Joe
             
            Last edited: May 22, 2022
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            • MOPAROFFICIAL

              MOPAROFFICIAL FABO Gold Member FABO Gold Member

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              You make a great point about the timing locked for the controller.
               
            • slidey06

              slidey06 Member

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              This is where we're at now after trying to adjust the IAC, it was at 0 at 160 degrees and stalled when I tried to adjust it. now when it starts, it idles erratically for a second and stalls. I brought the total timing down to 34 and disabled idle spark also. This looks like what I imagine interference looks like which is a common issue with the sniper. ERRATIC DATASET.jpg
               
            • Sr4440

              Sr4440 Active Member

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              Yeah, that isn't right.
               
            • oldkimmer

              oldkimmer FABO Gold Member FABO Gold Member

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              Plus having 7.0-1 compression doesn’t help either. Your cam probably isn’t doing u any favours. Kim
               
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              • MOPAROFFICIAL

                MOPAROFFICIAL FABO Gold Member FABO Gold Member

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                Doesn't matter if its fi , the timing wants to be higher at idle, like 20 btdc.
                Especially if you have low cyl pressure.
                15-16 isn't where I would run it.
                That thing should have a controller and what you put in all the parameters as in you set the timing in the controller the way you're actually running it so if it's let's say it's 18 at idle then you type in 18 and idle and if it's full Advanced at 34,35, or 36 ...you set that parameter. You also have to set the throttle blades evenly and have that parameter set too... so of you want 800 rpm idle... you have to dial the amount the the throttle blades are open then check the feedback/numbers are within what it calls for. You have instructions? Read them., more so... understand them.
                 
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                • 67Dart273

                  67Dart273 FABO Gold Member FABO Gold Member

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                  Also research your distributor position, and realize that with electronics, you are not actually talking about "advance" but rather, "retard." That is because advancing electronics would be like time travel. The electronics generates a pulse, and you cannot have the spark happen before the pulse happens. The distributor/ trigger device sends a pulse to the electronics, and the spark has to be retarded to happen AFTER the trigger.

                  What I'm getting at is two things, both related. The distributor (if you use one) has to be adjusted so that the rotor is phased with the ignition timing, and the electronics has to be adjusted to deal with "wherever the trigger pulse" is happening. Just a wild guess, but (including "vacuum" advance) the rotor needs to physically be about halfway in the middle or say, halfway from about 15--50 so "around" 30-35 degrees. This is set "static" with the engine stopped on that mark, and the rotor physically pointing "centered" on the appropriate tower contact and of course the mech/ vac mechanism locked out.

                  Otherwise, whatever you type into the program is meaningless (CHECK IT WITH A LIGHT!!!) and the rotor may be pointing to the moon when the spark happens "at the sun" So to speak.
                   
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