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Technical tuning 3x2 carb setup on a Y-block

Discussion in 'The Hokey Ass Message Board' started by 1LIFE2LIVE, May 1, 2015.

  1. ratryan
    Joined: Apr 8, 2010
    Posts: 16

    from NM

    Which Pertronix set up is it, Ignitor 2 or 3? Make sure your coil is compatible to the model you have. You can call them and they will verify. Sounds crazy I know, but I was there and hating life.

    The bad news is, I think you will need a mechanical advance Distributor. With a 3x2 setup, vacuum drops under acceleration, which is the opposite of what you need when using a vacuum advance. I fought the same crap, bought a MSD, blocked off the vacuum and the thing runs great. The new distributor with the pertronix installed is setting in a box somewhere.

    Maybe you will find a different way to make it work, but this was my experience. Good luck.

  2. sunbeam
    Joined: Oct 22, 2010
    Posts: 5,190


    The LSA of 107 will kill vacuum. Lumpy idle and good idle vacuum just don't go to together. Unless the end carbs throttle plates are completely closed and you do away with the idle curcuts you have just a vacuum leak.
    Last edited: Jul 5, 2018
  3. Its not a vacuum leak if you maintain the idle circuit. On my 312 I was pulling 14 with 3 idle circuits until I broke the Thunderbird cam and went to the Kilcup cam. The way we initially tuned the tri power was to shut the end carbs all the way down then adjusted the idle screws.

    This is not to say that I do not understand and agree with what you are saying. By that standard though you are saying that every engine has a very large vac leak because the throttle blades never shut all the way off on any carb except an end car specific carb.

    The selling point on the thumper cam is that it sounds nasty and is not. *It is supposed to maintain idle vacuum.

    *I cannot say this about the Big Mother Thumper I have not read the marketing material on that specific cam shaft.

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