Sierra 18-5475 Delco HEI Distributor for GM 4-Cylinder Marine Engines

The Sierra 18-5475 is a high-performance HEI (High Energy Ignition) distributor engineered for GM 4-cylinder marine engines equipped with Delco EST (Electronic Spark Timing) ignition systems. Part of Sierra's YLM Series, this distributor replaces original equipment marine distributors with modern, reliable technology built to withstand the demanding conditions of the marine environment.

This unit is a direct replacement for MerCruiser 817377 and serves as a drop-in solution for GM 3.0L inboard and sterndrive applications. The self-contained design integrates the amplifier and triggering device into a single assembly, eliminating the moving parts found in older ignition systems for improved longevity and reduced maintenance.

Key Features:

• Direct replacement for late-model GM EST distributor — replaces MerCruiser 817377
• Fits GM 4-cylinder marine engines with Delco EST HEI ignition
• Self-contained module/pickup assembly with no moving parts to wear out
• Durable aluminum housing replaces the weaker factory plastic housing
• Includes steel gear compatible with flat tappet and hydraulic roller cams
• Ball bearing and bushing combination for maximum timing stability and long service life
• Reliable high signal strength trigger system
• Meets or exceeds SAE J1171 marine ignition standards

The Sierra 18-5475 is engineered and tested to exacting specifications for marine use, delivering the dependable ignition performance needed in harsh saltwater and freshwater environments. Cross-reference OEM part numbers: MerCruiser 817377, GM 01103782.