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#1
08-19-2025, 04:17 PM
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Lean AFR at launch
Hope I am not wearing you guys out with all my questions. New data logging system is really interesting.
I only have two runs logged so far but when I am staged I bring my RPM up to approximately 4,250 rpm on my transbrake and my AFR is reading about 13.75 (I know thats a bit lean and have increased my jet sizes on both sides by +3) My issue/question is right after I release my transbutton my rpm drops about 470 rpm as the car goes under load and my AFR goes up to about 16.25 by approximately 0.4 seconds into the run. At 0.7 seconds my rpm is back up to about 4,400 rpm and my AFR is back down to about 12.5 Question - Is the spike in AFR due to too small a pump shot? I have a 750 Holley DP with a 28 Primary Shooter and 31 Secondary Shooter with Pink (330 Cam) on #1 position Carb also has 30cc pump on both sides. I have seen where Cliff R has suggested in some instances a 50cc pump on the Primary side is better. Any thoughts? Appreciate any and all of your thoughts especially your patience. DV
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1965 GTO Cameo White, Red Interior - 389, ST300 numbers matching 1965 GTO Black, Black Interior "Post" car - 389, M-20 numbers matching 1965 GTO Silver, Black Interior 100% dedicated drag car w/1968 400(461), 16x Heads, TH400, 3.90 9" Rear 1.656 60' 7.566 90.057 (1/8th) 1971 GTO Black (orig. Quezal Gold), Gold Interior - 400, TH400 numbers matching 1972 GTO Cardinal Red, Black Interior - 455, TH400 almost numbers matching |
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