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TBI, HEI, and distributors... Oh my!

Discussion in 'The Garage' started by jarheadk5, May 30, 2003.

  1. jarheadk5

    jarheadk5 1/2 ton status

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    OK, I see all these nice new HEI distributors in the Summit catalog, some advertised as being computer-compatible. Then I see stuff about vacuum advance and mechanical advance on those very same "computer-compatible" distributors, and I get a bit confused. I thought on 87-up TBI motors the advance was computer-controlled? Am I confused??
     
  2. ntsqd

    ntsqd 1/2 ton status

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    My guess is that they are confused, and that is confusing you. Make sense ?
     
  3. dyeager535

    dyeager535 1 ton status Premium Member

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    You are correct, and they may be too, if they are talking about the ESC only system like some of the trucks had.

    Really doubt thats what they mean though, can't imagine that would be a very popular product lol.

    Timing is controlled by the ECM even on the CCC carbed vehicles, as well as all the TBI and later stuff.
     
  4. jarheadk5

    jarheadk5 1/2 ton status

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    ntsqd: Yes, that confuses me.

    Dorian: So on an '87 TBI motor the initial timing is set by distributor position, just like any other app., but the advance is all done by the computer?
     
  5. CaveBlazin

    CaveBlazin 1/2 ton status Premium Member

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    Yep I would be confused too /forums/images/graemlins/grin.gif
     
  6. Thunder

    Thunder 3/4 ton status

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    On TBI the computer controls all the advance. Except base timing setting. There are no advance weights or vacume advance on TBI. Timing is controlled by input from VSS,MAP,Knock, and other sensors.
    The old coil in cap HEI will not work on TBI trucks even though they say its computer frendly.
    They will work on carbed trucks that are computer contorlled.
    There are only a few companys that make dists for TBI trucks
    I know MSD and Mallory make them.
    In my opinion the best aftermarket ones are these:performancedistributors.com The TBI Dists are at the bottom of the page.
    But acually the stock unit is a good dist. Unless the bushings are worn there is no sense in getting a new dist.. I upgraded my stock unit with DUIs 8 pin dyna mod and coil.
    Great mod for about 100.oo /forums/images/graemlins/thumb.gif More power, more torque It will rev over 5K no problem.
     

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