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Thread: Correct AFR check?

  1. 11-14-2018, 12:21 PM #1
    wicks
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    Correct AFR check?

    Hi all - drove my old 73 up to Big Sur to escape the fires over the weekend...she did a gorgeous job carving up the coast highway twisties, but she has a slight hesitation at part-throttle (full throttle no hesitation thankfully). The tailpipe is a bit sooty, but she does not blow smoke. My gut is that she's just a little rich, and maybe I should make a small adjustment to the MFI pump and see if she clears up. What's a good AFR test for a 73 911s engine? I had the MFI pump rebuilt a couple thousand miles ago and it was set up to stock flow specs and the space cam "looked good". CMA is all in spec.

    Tested at 12.7 AFR at idle and
    11.7 AFR at 3k RPMs

    This was just after a 5 minute warmup - so not heat soaked pump yet. And parked - no actual load. Don't know if I can just translate from CO to AFR or if it has to be under a driving load as in CMA to just get in the right ballpark.
    Last edited by wicks; 11-14-2018 at 02:24 PM.
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  2. 11-14-2018, 07:16 PM #2
    edmayo
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    At full throttle in third gear, fully warmed up I aim for 12.5 to 13.0
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  3. 11-15-2018, 10:14 AM #3
    wicks
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    Getting the tailpipe clamp so I can test under load.
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