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    Results 1 to 3 of 3
    1. #1
      Join Date
      Feb 2009
      Posts
      54

      minimum engine vacuum needed for EFI

      Hi
      have a 70 Firebird with a 30 over 455. The car produces 5 - 7" of vacuum at idle. Butler is telling me that that is too low for EFI systems to self tune and that I will need an expert with a lap top to get it to run properly. Can anybody comment on this...what is the lowest engine vacuum anyone has run on a street system that was able to self tune? What brand system was that?

      Thanks for any help/suggestions.

    2. #2
      Join Date
      Sep 2004
      Location
      Kettering, OH
      Posts
      537
      My EFI 462 ci Pontiac pulls about 10" at idle and is very streetable. The car idles fine at 700 rpm and while I'm not an expert, I did tune it myself versus relying on the self-tuning. 5-7" at idle sounds very low, but 10ish is definitely not a problem. Finally, I think self tuning is over rated, but it shouldn't be a problem at higher rpms. Also know that it doesn't set your afr or timing, only your ve, so you'll need to do some tuning anyways.
      1967 Firebird Convert, Fuel Injected 462 ci, TKO 600
      http://1967firebird.atwebpages.com

    3. #3
      Join Date
      Feb 2009
      Posts
      54
      Thanks for the feedback. Did a bit more reading and found the link to the Comp site where the definite opinion is that my vac is a bit on the low side and will need some manual intervention.





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