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Thread: GM Small Cap HEI TACH Question.

  1. #1

    Default GM Small Cap HEI TACH Question.

    Hi, I'm starting to wire a Dominator ECU to my small block.
    I elected to use a MSD 8366 small cap HEI distributor (no room for DIS coils).
    My intention is to control timing & dwell with the ECU (I'm removing an old MSD 6200).

    However, it's not clear where I should wire the TACH in the wiring diagram.
    It's a VDO tach & shift light that was triggered off the tach output of the MSD 6200 previously installed.
    Assuming I could just tap the negative between the coil and the distributor?

  2. #2
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    Default

    Quote Originally Posted by synackack View Post
    However, it's not clear where I should wire the TACH in the wiring diagram.
    If you're using a CD ignition box, see figure 4, page 12.
    http://documents.holley.com/techlibr...10555rev17.pdf (Holley EFI Wiring Manual)

    Without a CD ignition box, the tach wire connects to the negative coil terminal.






    http://www.megamanual.com/ms2/GM_7pinHEI.htm (MegaSquirt Ignition Module Information)
    May God's grace bless you in the Lord Jesus Christ.
    '92 Ford Mustang GT: 385" SBF, Dart SHP 8.2 block, TFS T/W 11R 205 heads, 232°-244° duration/.623" lift/114° LSA camshaft, 12:1 C/R, TFS R-Series FTI ported intake, BBK 80mm T/B, Dominator MPFI & DIS, 36-1 crank trigger/1x cam sync, 200A 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, -6AN fuel system plumbing, Walbro 255 LPH pump, S&W subframe connectors, LenTech Strip Terminator wide-ratio AOD/3000 RPM converter, B&M Hammer shifter, FPP aluminum driveshaft, FPP 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 M/T Street Comp tires.

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