Professional Ignition Integration for GM HEI Systems

The Holley EFI 558-304 ignition adapter harness is an essential component for those upgrading their GM Small Cap HEI distributor to work with advanced Holley EFI systems. Compatible with Avenger, HP, and Dominator ECUs, this harness provides a professional-grade connection that ensures your engine management system receives accurate crank and cam signals for precise timing control.

Why Choose the 558-304 Harness?

• Broad Compatibility: Works seamlessly with Holley Avenger, HP, and Dominator EFI platforms.
• Reliable Signal Path: Engineered to minimize electrical interference, ensuring stable timing under load.
• Factory-Style Connectors: Uses high-quality terminals that snap securely into place for a weather-resistant seal.
• Simplified Tuning: By providing a clean signal, this harness makes the initial setup and timing calibration of your EFI system significantly easier.

Don't let poor wiring compromise your engine's potential. The 558-304 harness is built to withstand the rigors of high-performance driving, featuring heat-resistant loom and durable wiring that stands up to extreme under-hood temperatures. Whether you are performing a full EFI conversion or simply upgrading your ignition, this harness is the reliable link your build requires. Find all your essential engine management components and wiring solutions at GGCRACING.