Struggling With Understanding Engine Timing Concepts

Discussion in 'Engine Topic' started by Bandit723, Jul 24, 2017.

  1. 71RS6SPD

    71RS6SPD Veteran Member

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    Nov 14, 2016
    I just started up my new SBC this year. I started at 32 @WOT and it was flat above 4000 rpm. I'm up to 36 now and it showed substantial improvement. Going to try more when the weather breaks - only 1k miles on it so far and was focused on carb tuning first.

    You should add vac advance for street driving. It has no effect during WOT. Improved throttle response, better mileage, cooler running, etc. Run with MANIFOLD vac - not ported vac. Idle timing advance should be in the 20's. Cruising/low/no load 2500 rpm should be around 50 advanced!
     
  2. bourbon_scotch

    bourbon_scotch Veteran Member Lifetime Gold Member

    2,017
    52
    Jan 10, 2003
    USA
    So your saying this distributor "knows" how to mechanically stop it at 28 degrees? So if you set it at 0 initial it would go to 28 degrees and stop there... or if you could set initial at 28 degrees it would just stay at 28 degrees? Do they make distributors with mechanical advance like that??
     
  3. FlaJunkie

    FlaJunkie Veteran Member Lifetime Gold Member

    5,896
    82
    Mar 24, 2001
    Rockledge, Florida
    Engine timing...gosh I have forgotten a lot about it. I use to have a screamer with the stock Z28 point distributor.
     
  4. secondgenaddict

    secondgenaddict Veteran Member

    137
    7
    Dec 29, 2012
    Upstate South Carolina
    MECHANICAL ADVANCE IS BEST LEFT FOR THE RACE TRACK, where the engine operates in a limited number of scenarios...
    For street use go with the Vacuum advance distributor with the Vacuum hooked to FULL manifold vacuum(below the throttle blades). PORTED will allow the timing to "dither" up and down, causing the RPM's to float around making the vacuum signal above the throttle plates, which when the RPM drops causes the vacuum above the plates to fall below what is required to keep the power valve closed (fuel for a load transition) the engine gets too much fuel and either lugs or loads up.
     
    FlaJunkie likes this.

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