An EFI system depends on a clean, constant voltage source, and grounds are just as important as the power side. This universal Holley harness kit includes the main harness, power harness, and injector harness needed to support your primary V8 MPFI system.
Specifications:
- Harness Application: Ford, GM, Universal
- Ignition Type: CD Ignition (No Timing Control)
- Injector Connector: Jetronic/Minitimer (Bosch)
- Includes: Main power harness, MPFI main harness, V8 injector harness
- Product Type: Harness Kit
- Part Number: 558-504
Works with Dominator and HP ECUs. To complete your installation, add a Holley ECU and a compatible oxygen sensor.
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 vehicles is the 558-504 harness kit compatible with?
It's a universal harness for Ford, GM, and other V8 MPFI applications.
Does it include an ECU?
No, pair it with a compatible Holley ECU and oxygen sensor, both sold separately.
What ignition type does it support?
CD ignition with no timing control.
What's included?
Main power harness, MPFI main harness, and V8 injector harness.

