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Thread: Terminator with FAST Dual Sync & CNP?

  1. #1

    Default Terminator with FAST Dual Sync & CNP?

    I just purchased a Holley Terminator EFI for my '66 GTO. I have a FAST Dual Sync and would like to run it with Coil-Near-Plug ignition. I couldn't find an exact match on this forum, but is all I need the following harnesses:
    558-307 CNP Main Harness
    558-313 FAST Dual Sync Harness
    Or would I have to purchase a different type of main harness? Thanks.

  2. #2
    Join Date
    Dec 2009


    Yes, you'll need those two harnesses.

    If you already have or you're purchasing a new Holley non-LSx main harness:
    The Holley 558-307 CNP main harness is for Holley's Coil-On-Plug smart coils and LSx ignition coils.
    If using Holley's 556-112 CNP coils, Holley's 558-318 CNP coil sub-harness is also required (or Holley 556-128 CNP V8 Kit).
    For LSx ignition coils, the Holley 558-307 CNP main harness plugs right into the two GM 12579355 CNP sub-harnesses.
    IF you had an LSx main harness, you wouldn't need the Holley 558-307 CNP main harness or the 558-318 CNP coil sub-harness. (Holley EFI Coil-Near-Plug Ignition Components) (Holley EFI 556-128 Coil-Near-Plug Big Wire V8 Kit) (Holley EFI 558-117 Universal MPFI Coil-Near-Plug Main Harness) (Holley EFI 558-118 Ford Universal MPFI Coil-Near-Plug Main Harness) (Detailed Crank Trigger & CNP/DIS Conversion Information & Reasoning)
    May God's grace bless you in the Lord Jesus Christ.

    '78 BRONCO: 508" stroker, TFS heads, 11:1 comp ratio, Dominator MPFI & DIS, cold air induction, Spal dual 12" fans/aluminum radiator, dual 3" exhaust/Magnaflow mufflers, Moroso vacuum pump, Accusump, engine oil & trans fluid coolers, 100HP progressive dry direct-port NOS, A/C, LenTech Strip Terminator wide-ratio AOD/2500 RPM converter, 3:1 Atlas II, modified Dana 44/60-lockers-4.10s, hydroboost/4-disc brakes, ram-assist/heim joint steering, Cage long radius arms, traction bars, 4" Skyjacker lift, 35" mud tires

  3. #3
    Join Date
    Nov 2014
    Ont. Canada


    I run a FAST dual sync & CNP. What I don't like about the FAST dual sync distributor is at the base of the aluminum shaft where the gear is, it's a little different than the Holley. The housing is not tapered, so the distributor can not go as deep into the engine before the housing hits the cam gear. I had to pull the distributor apart and grind a taper in the housing, to allow the distributor to go in deep enough to give me a good distributor gear to cam gear mesh. If I didn't do this the wear pattern on the distributor gear was way too low on the gear. Before you put it together check your distributor height & wear pattern.

  4. #4


    Thanks to both of you. I didn't know that about the FAST distributor. Thanks, I will check that.

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