This "Big Wire" ignition sub harness is pre-wired with 12-gauge power and ground wires for optimal performance in high-current ignition applications.
Specifications:
- Wire Gauge: 12-gauge power and ground wiring
- Harness Type: Ignition sub harness (C-N-P / HP Smart Coil compatible)
- Part Number: 558-318
Compliance: This part is legal for sale and use on Racing Use Only Vehicles — competition vehicles that are not registered and never operated on the street. It is against the law to install this part on an Emissions Controlled Vehicle (1966-and-newer California-certified or 1968-and-newer federally certified vehicles).
FAQ
What makes this a "Big Wire" harness?
It's pre-wired with heavier 12-gauge power and ground wires rather than standard-gauge wire, supporting optimal current delivery for the ignition coils.
What is this harness used with?
It's a sub harness for Holley EFI HP Smart Coil ignition setups, feeding power and ground to the coil-near-plug ignition system.
Is this harness legal for street use?
No. This part is legal for Racing Use Only vehicles and is not for installation on emissions-controlled street vehicles.
Does this harness include the main harness connectors?
This is a sub harness intended to work alongside the corresponding main engine harness; it is not a standalone main harness.

