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Thread: factory digital tach

  1. #1
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    Default factory digital tach

    Some time back I saw a post that someone had added a diode to the tach. this was to have it read correctly for a v8, anyone remembers the post? someone mentioned "archive"?

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    That won't do anything. You can try to make the tach accurate with one of these. The problem is that our Tachs are for V6's, because they come from Aerostar. Our cars (with digitachs) have V8's. The Dakota Digital interface interprets the 8 cyl tach signal coming from the coil, and then sends a 6 cyl tach signal to the cluster. In this way, the interface corrects the number of pulses so that the tach is accurate. You'll have to program it, as the unit is meant to be universal.
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    1988 Thunderbird 5.0
    GT40P, TFS-1, KB domes, 30#, MAF conversion, Explorer GT40 Upper/Lower, Smog delete, Wide Ratio AOD Mod, Unlocked Speedo, 3G Charging System Upgrade, Hi-Torque Mini Starter, 3.73 LSD, BBK 1 5/8 unequal headers, H-Pipe.

    88 Thunderbird/Cougar EVTM
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    I need to do this still. So I can ditch the Autometer tach.

    But yes the factory digital tach is pretty much dead on for a 6 cylinder. If I set my Autometer tach to 6 cylinder mode it matches the stock tach exactly in my car.
    '88 Thunderbird LX: 306, Edelbrock Performer heads, Comp 266HR cam, Edelbrock Performer RPM intake, Edelbrock 70mm TB, 76mm C&L MAF, 30lb injectors, 2.5" exhaust, AOD with 2800 PI converter, 8.8 with 3.73 gears, 31 spline Traction-Lok, 31 spline Moser axles, 04 Cobra front arms, Maximum Motorsports extreme duty rear arms, subframes.
    '11 Focus, '12 Mustang 3.7, '17 Accord EX-L V6

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    Quote Originally Posted by TheFoeYouKnow View Post
    That won't do anything. You can try to make the tach accurate with one of these. The problem is that our Tachs are for V6's, because they come from Aerostar. Our cars (with digitachs) have V8's. The Dakota Digital interface interprets the 8 cyl tach signal coming from the coil, and then sends a 6 cyl tach signal to the cluster. In this way, the interface corrects the number of pulses so that the tach is accurate. You'll have to program it, as the unit is meant to be universal.
    I was just thinking about this the other day. I'm trying to remember where one can tap into the output signal from the coil before the instrument cluster harness. I'd rather not tap into the wiring directly behind the instrument cluster but instead somewhere under the dash.
    '88 Thunderbird LX: 306, Edelbrock Performer heads, Comp 266HR cam, Edelbrock Performer RPM intake, Edelbrock 70mm TB, 76mm C&L MAF, 30lb injectors, 2.5" exhaust, AOD with 2800 PI converter, 8.8 with 3.73 gears, 31 spline Traction-Lok, 31 spline Moser axles, 04 Cobra front arms, Maximum Motorsports extreme duty rear arms, subframes.
    '11 Focus, '12 Mustang 3.7, '17 Accord EX-L V6

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    The DG/Y in C294 only goes to the cluster, You should be able to intercept it there.
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    1988 Thunderbird 5.0
    GT40P, TFS-1, KB domes, 30#, MAF conversion, Explorer GT40 Upper/Lower, Smog delete, Wide Ratio AOD Mod, Unlocked Speedo, 3G Charging System Upgrade, Hi-Torque Mini Starter, 3.73 LSD, BBK 1 5/8 unequal headers, H-Pipe.

    88 Thunderbird/Cougar EVTM
    (Thanks to Trinom for hosting)

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    Ah cool. Was hoping to do it under the dash but that'll work. Now to buy the damn box .

    When I do this I'm leaving the Autometer tachometer in place to verify the accuracy of the modified stock tachometer. If it's close I'll remove the Autometer unit.
    '88 Thunderbird LX: 306, Edelbrock Performer heads, Comp 266HR cam, Edelbrock Performer RPM intake, Edelbrock 70mm TB, 76mm C&L MAF, 30lb injectors, 2.5" exhaust, AOD with 2800 PI converter, 8.8 with 3.73 gears, 31 spline Traction-Lok, 31 spline Moser axles, 04 Cobra front arms, Maximum Motorsports extreme duty rear arms, subframes.
    '11 Focus, '12 Mustang 3.7, '17 Accord EX-L V6

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    Ive been lied to!!!!!! Is it reading high or low?
    Mike

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    We've all been lied to. It reads 25% high, so the higher you rev, the further off the tach gets.
    1988 Thunderbird 5.0
    GT40P, TFS-1, KB domes, 30#, MAF conversion, Explorer GT40 Upper/Lower, Smog delete, Wide Ratio AOD Mod, Unlocked Speedo, 3G Charging System Upgrade, Hi-Torque Mini Starter, 3.73 LSD, BBK 1 5/8 unequal headers, H-Pipe.

    88 Thunderbird/Cougar EVTM
    (Thanks to Trinom for hosting)

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    I guess that is better than reading artificially low and actually over revving the engine.
    Mike

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    first i heard someone say its not off in a linear way.... but is off more and more the higher R's.

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