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Thread: Sniper in a 1968 GT Mustang

  1. #1

    Default Sniper in a 1968 GT Mustang

    Hi all. I'm in the middle of installing my Sniper on a 1968 GT Mustang convertible. Car is 302, automatic with factory tach. I'm running an MSD 6AL box with a 8920 tach adapter. I see the wiring in the Holley manual for a CD box, however, it doesn't say anything about my tach adapter (can't account for all the variations out there). I'm trying to avoid a costly tach rebuild in the event of a miswired situation. Can you tell me how to handle the wiring with the tach adapter? Many thanks for all you do on this site! Walt

  2. #2
    Join Date
    Jul 2014
    Location
    Aptos, CA
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    99

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    Why not just use the Brown wire in the 10-pin connector to run your tach and by-pass your tach adapter? I just installed one on a 331 SBF with Dual Sync and 6AL box and used the Brown wire (pin G) to run the tach (Speedhut) and it works just fine. I know the wiring diagram says to come from the CD box, but after a quick call to Holley they verified you can use the Brown wire. I have a wiring diagram I can send you when I return home tomorrow if you're interested.

  3. #3

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    The difference is a factory tach NEEDS the tach adapter to work. Aftermarket tachs work fine off the brown wire, not factory tachs. The Holley wiring is just connecting to the input side of the MSD box. The tach output of the MSD box won't be effected. If your tach works now, it will work after connecting the Sniper.

  4. #4

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    Danford1, thanks for your input. So, do I just connect BOTH the white wire from the tach adapter AND the purple wire from the Holley Ignition adapter into the spade connector for tach output on the MSD 6AL? Basically, is it OK to clamp and solder both wires together in a spade connector to attach to the tach output? Thanks, Walt

  5. #5
    Join Date
    Dec 2009
    Location
    Connecticut
    Posts
    22,694

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    I didn't read all this, but the dark brown wire is the Tach Output: http://documents.holley.com/199r11031r.pdf (Holley Sniper EFI Instruction Manual - "ECU Wiring Overview", Page 16 & "10 Pin Connector", Page 17)
    May God's grace bless you in the Lord Jesus Christ.
    '92 Ford Mustang GT: 385" SBF, Dart SHP 8.2 block, TFS TW 11R 205 heads, 11.8:1 comp, TFS R-Series intake, Dominator MPFI & DIS, 36-1 crank trigger/1x cam sync, 160A 3G alternator, Optima Red battery, A/C, 100HP progressive dry direct-port NOS, Spal dual 12" fans/3-core Frostbite aluminum radiator, Pypes dual 2.5" exhaust/off-road X-pipe/shorty headers, S&W subframe connectors, LenTech Strip Terminator wide-ratio AOD/2800 RPM converter, M4602G aluminum driveshaft, FRPP 3.31 gears, Cobra Trac-Lok differential, Moser 31 spline axles, '04 Cobra 4-disc brakes, '93 Cobra booster & M/C, 5-lug Bullitt wheels & 245/45R17 tires.

  6. #6

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    Quote Originally Posted by 68GTConvert View Post
    Danford1, thanks for your input. So, do I just connect BOTH the white wire from the tach adapter AND the purple wire from the Holley Ignition adapter into the spade connector for tach output on the MSD 6AL? Basically, is it OK to clamp and solder both wires together in a spade connector to attach to the tach output? Thanks, Walt
    Oh Boy, I can’t answer this exact question. Personally I would call Holley tech support and ask them. I don’t think anyone here is familiar with tach adapters for factory tachs. They only seem to think everyone is using an aftermarket tach. Danford1

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