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mechanical or vacuum

Discussion in 'The Hokey Ass Message Board' started by racerboy79, May 18, 2012.

  1. I have built an A with a totally stock 260 horse GM crate engine with 2 Demon 2 barrels. It has a 350 trans and a 3.73 rear end. Do you guys like mechanical or vacuum advance? Thanks for your time.
     
  2. mechanical for racing.vacuum and mech together for street.vacuum will help mileage.A stock GM HEI dist with both is perfect.
     
  3. GassersGarage
    Joined: Jul 1, 2007
    Posts: 4,729

    GassersGarage
    Member

    Get an original GM distributor and convert it over to electronics. HEI's look terrible on a rod.
     
  4. JOHNPO
    Joined: Dec 1, 2010
    Posts: 76

    JOHNPO
    Member

    I prefer mechanical. I like to use Mallory unilite reason small and clean and haven’t had a problem with one yet. Had them in all my rods. I also have installed their point conversion kit in my wife’s 71 Torino that was 18+ years ago still running strong.
     

  5. Aquaroscoe
    Joined: Apr 13, 2006
    Posts: 315

    Aquaroscoe
    Member

  6. squirrel
    Joined: Sep 23, 2004
    Posts: 47,160

    squirrel
    Member

    When gas was 28 cents a gallon, vacuum advance wasn't a big deal. Now that gas is close to $4 a gallon, it pays for itself.
     
  7. Relic Stew
    Joined: Apr 17, 2005
    Posts: 1,129

    Relic Stew
    Member
    from Wisconsin

    If you're hard on the throttle all the time, like racing or a power boat, vacuum advance doesn't do much.

    If you cruise around at part throttle the vacuum advance is needed to maintain efficient combustion. At low cylinder pressures encountered at light throttle, the flame front travels much slower, so more ignition advance is needed to get peak combustion pressure at the ideal time.

    I don't think any modern distributors are just vacuum, so its not " vacuum or mechanical". Modern stock distributors have both.
     
  8. squirrel
    Joined: Sep 23, 2004
    Posts: 47,160

    squirrel
    Member

    "modern" meaning late 50s to mid 80s when ignition all became computer controlled.
     
  9. Jalopy Joker
    Joined: Sep 3, 2006
    Posts: 25,516

    Jalopy Joker
    Member

    yep. no HEI - update older style small cap vac/mech distributor to electronic. 3:73 rear gears pretty low for a mild motor and 350 trans unless you have real tall rear tires.
     
  10. Relic Stew
    Joined: Apr 17, 2005
    Posts: 1,129

    Relic Stew
    Member
    from Wisconsin


    Yeah, "H.A.M.B. modern", not "21st century modern".:D
     
  11. Thanks guys, you have been very helpful!
     

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