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  1. #1
    @md0Cer's Avatar
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    Tachometer Installation

    I was wondering, on an older car without a tachometer, would it be fairly easy to install one of those 50 dollar thingys from a local auto parts store?

    I already know it is either wired to a "coil" or the "ECU" if it is a newer car, but the main concerns are:

    1.) Does the car already have a tachometer? It has to because that is the only way it knows what to idle at and what speed it currently is idling at. When the revs drop too low it evens it out.

    My current thinking is that all cars have a "tachometer" just some of the crappier ones just don't display it in the instrument cluster. True?

    2.) If it did, how would I take the dash apart to get the wires to this thing? I wouldn't even know where to start.

    If anyone can help, that would be nice. Thanks.
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  2. #2
    Is the car that you are planning installing the tach a manual or an automatic?

  3. #3
    Member Cyrix_2k's Avatar
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    How old? My Dad's 1969 and 1977 442's both have their tach's wired into the coil, which makes for a very simple/easy installation. I have no idea about newer cars.

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  4. #4
    @md0Cer's Avatar
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    Manual transmission and it is a late 80's.
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  5. #5
    Senior Band Wagon Jumper CrystalMethod's Avatar
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    What car though? The late 80's was a mix of different ignition types.

  6. #6
    @md0Cer's Avatar
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    VW Golf
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  7. #7
    Member zip22's Avatar
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    how do you guage when to shift without a tach? just speed and engine noise?

    not really related, but im curious

  8. #8
    engine noise

  9. #9
    Member AFIsoldier's Avatar
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    Good question, sorry to jack...but what would the circumstances be for adding a Tach to an '83 F-150 w/ 302 and Auto-trans?

  10. #10
    @md0Cer's Avatar
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    Engine noise. Also in the manual they give you speeds for each gear to shift normally for economy and then redline.
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  11. #11
    Senior Band Wagon Jumper CrystalMethod's Avatar
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    Gah! You're gonna make me look stuff up aren't you?

  12. #12
    @md0Cer's Avatar
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    no. I am just trying to find out if all cars actually have a "tachometer." I have been looking stuff up, and im not sure if you will have any better luck than I have.

    Still, no matter what the ignition type, there has to be something counting the revs so it can idle, etc.
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  13. #13
    @md0Cer's Avatar
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    Ok, I found a nice link on Tachometer installation:

    http://hp.autometer.com/instructions...nstruction.pdf
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  14. #14
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    No, not all cars have a tachometer hidden. They can tell what they are idling at through sensors, and there isn't really a way to get access to those sensors without using diagnostic systems. If you want to install a tach, then you have to wire it all. It isn't really hard, the hardest thing is getting the wires from the tach to the engine bay/compartment. Also, most tachs include a decent installation guide, plus you already found a guide.
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  15. #15
    @md0Cer's Avatar
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    Ok. I doubt this has an ECU, so if I can find the coil, it should be pretty easy then.
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    A cars RPM's are controlled by a cable or hydrolics attached to the gas pedal, essentially. For a carb by pressing this down you are sending a "signal" basically controlling a valve, allowing more gas and air to flow thus increasing the rpms. When the linkage (in case of my bug) isn't being pushed down all the way, preset screws that control the idle come into play. For EFI your basically sending a signal that tells the comp to squirt more fuel and open up a little for more air.
    A tach is merely a gauge that tells how many rpms the engine is creating.
    If you locate the distributor the coil will be connected via that wire in the center of your distributor. If you can't find the distr follow the wires.
    However, beware that not all Tach's are created equal. I personally like Autometer and VDO. There are others out there as well.

  17. #17
    @md0Cer's Avatar
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    Ok, thanks.
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  18. #18
    Senior Band Wagon Jumper CrystalMethod's Avatar
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    Quote Originally Posted by NewbiePerson
    A cars RPM's are controlled by a cable or hydrolics attached to the gas pedal, essentially. For a carb by pressing this down you are sending a "signal" basically controlling a valve, allowing more gas and air to flow thus increasing the rpms. When the linkage (in case of my bug) isn't being pushed down all the way, preset screws that control the idle come into play. For EFI your basically sending a signal that tells the comp to squirt more fuel and open up a little for more air.
    A tach is merely a gauge that tells how many rpms the engine is creating.
    If you locate the distributor the coil will be connected via that wire in the center of your distributor. If you can't find the distr follow the wires.
    However, beware that not all Tach's are created equal. I personally like Autometer and VDO. There are others out there as well.
    Gotta be careful with the information you're giving out. Some EFI systems use the crank position sensor and a cam position sensor to guage the RPM. Some take the reading from the ICU under the coil packs (if you have them), others will run directly off of the distributor or coil. Some cars you can completely remove the head with the distributor put power to the starter and still get a tach signal because it's reading from the crank sensor. The absolute best idea is to get the shop manual and check the wiring diagram.

  19. #19
    Member stockhatch's Avatar
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    Quote Originally Posted by zip22
    how do you guage when to shift without a tach? just speed and engine noise?

    not really related, but im curious
    3rd pop of the rev limiter

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  20. #20
    @md0Cer's Avatar
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    Not all cars have rev limiters.

    And thanks for the info CM.
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