Pay in installments of $97.50 with
,
and
Shipping Estimate
USA
- USA
- CAN
- USA
- CAN
Ships within 48 hours · Estimated delivery Sep 17 - Sep 22
Promo Codes Available:
For Your Every Summer RSVP, with Code: SUMMER15
Description
Holley Coil-Near-Plug Smart Ignition Coils 556-128KIT, BIG WIRE 8 CYLINDER SMART COIL KIT 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+
KIT, BIG WIRE 8 CYLINDER SMART COIL KIT
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
Features:
- “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!
Application
-
Universal
Specs
| Brand | Holley EFI |
|---|---|
| Emission Code | 4 |
| Height | 1.86" |
| Ignition Wire Terminal Type | HEI Style Tower |
| Mounting Bolt Pattern | 74mm |
| Overall Length | 4.3" |
| Product Type | Distrutorless Ignition - DIS - smart coil |
| Width | 3.6" |
| Part Number | 556-128 |
Shipping Notes
- Free Standard Shipping on $100+ Orders to the USA.
- Except Preorder products are shipped in 48 hours.
- Delivery to the USA:
- Standard Shipping : 3-10 business days
- If time is of the essence, please consider selecting expedited delivery for faster service.
Exchange/Return Notes
- We offer a 30-day return/exchange service after receiving.
- Final sale items are not eligible for returns or exchanges.
- To process your return/exchange, please contact us at [email protected]
- Please click here for more details>>> Return & Exchange Policy
4.8 ★★★★★
Based on 12 reviews
Sort
Product Reviews
★★★★★ 5
real time and energy saver, as well as $
Size: 16AWG Wiring Harness-2 Leads
If you have a set of LED lights that didn't come with a harness , you can't beat this for the price. By the time you figure in the cost of the parts ( wire, switch, crimps/connectors, not to mention a relay if you are using one) to hardwire a set of lights, let alone the time to assemble, this set up is cheaper by far. harness length is ample, you get a pair of pigtails with connectors for a pair of lights, the relay, switch, fuse block and fuse, and ring terminals for power all assembled for what a switch and some wire would cost. Made everything quick, cheap, and easy.
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on October 17, 2024
★★★★★ 5
Great wiring harness for light installations.
Size: 16AWG Wiring Harness-2 Leads, Size: 16AWG Wiring Harness-2 Leads
This is a great wiring harness for LED lights. These come in one or two leads application. All that means is that they come ready for one or two lights, depending on your installation. The plug in connectors for each light comes with the set so that is a plus. I’ve attached a picture of the plug/connector for the lights so you can take a look at them. Although the relay is an “overkill” for low wattage LEDs, it’s OK to have it just in case you decide to change your lights for larger ones or halogens, in the future. In my case I will be using this harness in my motorcycle. It is very long for my need, which is great for cars, but too long for motorcycles since you have to remember that room/space is scarce in motorcycles. I ended up cutting the wires to my desired length and using heat shrink butt connectors and “glued” heat shrink covers for waterproofing the connection points. All in all these are great quality and I am very happy with them.
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on December 16, 2020
★★★★★ 5
Nice
Size: 16AWG Wiring Harness-2 Leads
Worked great, easy to install
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on January 8, 2026
★★★★★ 4
Wire length between the two connectors is short for a full-size pickup
Size: 16AWG Wiring Harness-2 Leads
I used the harness to wire ditch lights on opposite sides of a full-size pickup (F150). The wire between the 2 2-pin connectors was about 18 inches too short. Fortunately, splicing the wires from the (Nilight) ditch lights and the included pigtails gave barely enough length to reach the connectors. The connectors are buried inside the trim channel for the cowl; I'd have preferred they were exposed on each side to allow for easy swapping of the lights, but I can live with it. There is more than enough wire from the first connector to the relay for my all-under-hood installation, but I didn't think to measure if it would reach into the truck bed. The harness is of good quality and is a very good value. It would be a 5-star if it weren't for that little length issue.
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on June 1, 2025
★★★★★ 5
great value
Size: 16AWG Wiring Harness-2 Leads
very affordable light install kit. worth the price just in the wiring connectors. I used this with my Nilight front bumper kit. i bypassed the button and wired high beam (+) to the yellow small wire. I did this so when the highbeams come on the light bar comes on. because with the stock arragement of this harness, the button continously draws power for the indicator LED
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on April 30, 2026