Single distributor/DIS signal divider for Tach | FerrariChat
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Single distributor/DIS signal divider for Tach

Discussion in '308/328' started by dan the man, May 7, 2007.

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  1. dan the man

    dan the man Karting

    Nov 5, 2003
    146
    Alabama
    Full Name:
    Daniel
    #1 dan the man, May 7, 2007
    For all of you who have converted from dual distributors to single or have converted to a DIS system but need to divide the signal to the tach so it works (from a V8 to a 4 cyl signal); is there a market for a tach signal divider?

    I have had to build one, and I am using it (still on the test board). It works great, and I have not had any issues with it even on the test board (about 6000 miles or so). I will eventually put it on a PCB and such, and am wondering if people are in need of this or not.

    This item will be part of my carb to FI conversion kit, but I want to know if it is needed elsewhere.

    just throwing it out there.

    Dan
     
  2. rufus

    rufus Karting
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    Nov 6, 2003
    151
    Toronto & St PetesFL
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    Pete Gorrell
    #2 rufus, May 7, 2007
    I think most of us who have gone to a single distributor have sent our tach to Palo Alto Speedometer... The price had gone up to $250 + shipping (roughly, my best recollection) a couple of years ago. I thought that was a bit expensive for a chip replacement.
     
  3. racespecferrari

    racespecferrari F1 Veteran

    Jan 31, 2006
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    Pete.G By The Sea
    #3 racespecferrari, May 8, 2007
    Site sponsor Nicks Forza already supplies one with his Electromotive Xdi kit
     
  4. ants2au

    ants2au Formula Junior

    Nov 19, 2003
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    Sydney Australia
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    Anthony
    #4 ants2au, May 8, 2007
    does this mean that there are 2 versions of the Tachs out there? one for euro cars and one for the rest?

    I always thought that the tach pics up from one of the two coils. Even if you have one distributor, you still have two coils. that is, tach always sees 4cyl.


     
  5. racespecferrari

    racespecferrari F1 Veteran

    Jan 31, 2006
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    Pete.G By The Sea
    #5 racespecferrari, May 8, 2007
  6. Birdman

    Birdman F1 Veteran

    Jun 20, 2003
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    THE Birdman
    #6 Birdman, May 8, 2007
    It is my understanding that the carb cars have a high voltage tach, using ~100v signal from the coil to run it and the injected cars have a low voltage tach, using a ~12v signal from the ignition ECU to run it.

    The "black box" for the tach that Nick provides in his kit is actually an amplifier. The XDI directly provides a "4 cylinder" tach output if you need it, but it's 12 volts and must be amplified to ~100v to run the tach on a carb car.

    Birdman
     
  7. dan the man

    dan the man Karting

    Nov 5, 2003
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    Alabama
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    Daniel
    #7 dan the man, May 9, 2007
    Birdman,

    Does that mean the ECM sends out a 12V V8 signal to the tach (vs the earlier 4 cyl signal)? Are the carb'd cars the only ones who need a divider?

    I believe what I have will work in both cases as it only divides the signal (from 8 to 4). I also have to run an amplifier (MSD) for my tach, mine being a 79 carb'd 308.

    Not all of us have purchased their DIS systems from Nick's. I have found him to be very helpful when I have contacted him about parts etc, but I actually bought my Electromotive unit from a performance shop relatively close to my home which used it on their engine dyno. They were upgrading to a newer type of electromotive DIS and was no longer using it. It was a lot cheaper than buying one new, and it came with a cam sensor which was easier (but uglier) to deal with and install. But, this meant I had to build a signal divider for the tach.

    I do not know much about the singal distributor setups. I did not realize they still used two coils. If this is the case, I would suspect they do not need a divider.

    Anyway, I was not sure if it was worth the effort to make this into something you guys could use.

    Thanks,
    Dan
     

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