TUNING A SIX PACK

A12 Mopar Discussions

  1. RJRENTON

    RJRENTON FBBO Gold Member FBBO Gold Member

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    I'm aware of the differences, and the reasons for the differences. But the origional question, I believe, was the diaphragm assembly shown in the pix would/could be used for a six barrel application....which is NO.
    The use of a needle valve is innovative, but accuracy and consistency of the adjustment may be questionable and will the adjustable factor also slow the closing rate, in addition to the opening rate? And how will the setting be determined.....empirically or ?
    BOB RENTON
    BOB RENTON
     
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    • 66Satellite47

      66Satellite47 FBBO Gold Member FBBO Gold Member

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      I was just making a clarification about the diaphragms. Yes like many tuning adventures, the needle valve adjustment is trial & error, it provides some "fine tuning" without needing to change the springs. And as with many tuning things, they may not remain constant over time. Never considered the effect on closing rate since mine was a drag car application.
       
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      • Frustration

        Frustration Well-Known Member

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        Well, our track rental got rained out Memorial Day Weekend. It was rescheduled for yesterday in the 95 degree heat. We had 46 cars show up at Cecil County...mostly mopar, but other brands as well. Everyone was off at least three tenths due to the heat and track condition. My son was driving and made eight passes. We found lots of stuff that we did not see on the dyno. For example, the car developed a serious bog off the line that was not evident on the dyno, and didn't happen before. Guessing it was because of the fatter tune up. Tried different squirters and bringing in the accelerator pump a bit later. That seemed to help. At the end of the day, we ran a best of 11.39 @119. Pretty good, but with the 60' being off more than a tenth, that will be my area of focus moving forward. As a bonus, Tommy made it to the final for the second year in a row. He was unable to defend his title as he lost to a great racer who ran dead on with a zero in the final. I'll try to post the video here shortly.
         
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        • biomedtechguy

          biomedtechguy Accelerati Rapidus Maximus FBBO Gold Member

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          Thanks for the clarification on the needle valve controlled vacuum pods. I had asked...someone...about the particular one pictured and was told "not compatible" but I thought there may be one.
          I've been lucky that is one area I don't have problems with, the rate and conditions that my outboard carbs open. Whether I stomp from a dead stop or roll into the outboard carbs, it works well.
          One day I may make the time to tune with my O2 sensor system. It's running fat at "cruise" throttle positions, around 11.8-12.1
           
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