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Holley 556-128 Big Wire Coil Near Plug Smart Coil Kit
Holley 556-128 Big Wire Coil Near Plug Smart Coil Kit

Holley 556-128 Big Wire Coil Near Plug Smart Coil Kit

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Holley 556-128 Big Wire Coil Near Plug Smart Coil Kit
Holley 556-128 Big Wire Coil Near Plug Smart Coil Kit
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We estimate this item will ship on or before March 21st.
Part # 425556128
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Important Messages:

  • This item ships directly from the manufacturer. It may take an additional 2 business days for Holley to ship this item.
  • Get FREE shipping when your order includes this item and exceeds $99! Ground shipping only in the contiguous US.
  • This item ships via Ground Shipping only. Expedited and Air shipping options are not available.


MFG. Part #:
Maximum Voltage:
44000 volts
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Do you need precision control over your ignition system? Would your combination benefit from Individual Cylinder Timing Control? Are you experiencing spark issues with your Stock Coils? Are you wanting to convert your Turbocharged Big Block Monstrosity to Coil-Near-Plug?! Problem solved, introducing the Holley EFI Big-Wire C-N-P Kit containing everything you need to upgrade your ignition system to handle 5.5+ HP per Cubic Inch

  • “Big Wire” Sub Harness- Pre wired with 12ga Power and Grounds, for optimal performance
  • Peak Voltage – 44,000 Volts
  • Peak Output – 102 Mj
  • Maximum Battery Voltage 17.0 Volts
  • Upgrading a Non C-N-P Main Harness requires the Holley Universal Coil-On-Plug Harness, P/N 558-307 to complete the installation
  • Contains two Terminated Sub-Harnesses, and Eight Holley Smart Coils, 3 ft. of wiring loom for a professional appearing installation
  • Sub Harness features Fully Terminated Coil Connectors, a 7 Pin Metripak Connector used on several Holley EFI C-N-P Main Harnesses, and 3 loose wires for a quick installation

Installation Instructions (PDF)

Some parts are not legal for use in California or other states with similar laws/regulations


Q & A

Videos & Articles
  • Pat talks about our red solid core spark plug wire and rajah ends.
  • Looking for an easy performance upgrade to your ignition system? MSD's line of Ignition Control Boxes offer extreme improvements to drivability and high rpm applications. Here's a look at the differences between the 6 series line-up.
  • Get the best out of your ignition system! Here we take a look at some of the differences between factory plug wires and the improvements you'll receive with a quality set of aftermarket performance wires.
  • Speedway Motors employee Tim M. Decided to take us along as he revives his 241 "Baby Hemi". In this installment, Tim walks us through updating the old wire covers with a nice set of Offenhauser Finned Wire Covers.
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