Delco Rotor | Sierra 18-5418

Sierra Delco Ignition Rotor | 18-5418 | 4 & 6 Cylinder | OMC Mercury Universal

The Sierra #18-5418 is the replacement ignition rotor for Delco single-point marine distributors on 4-cylinder and inline 6-cylinder engines. Fits conventional ignition systems with Delco distributors on OMC, Mercury, and Universal marine engines. Replaces OMC 384735, Mercury 58217/58217Q/898253008/8M6001251, and Universal 288702.

Part Details:

• Part Number: 18-5418 (Sierra)
• SKU: SIERRA-18-5418
• Manufacturer: Sierra
• Type: Ignition Rotor — Delco Distributor
• Fits: 4-cylinder and inline 6-cylinder Delco single-point marine distributors
• Ignition Type: Conventional (points-type)
• Condition: New

Cross-Reference — Replaces:

• OMC: 384735
• Mercury: 58217, 58217Q, 898253008, 8M6001251
• Universal: 288702

Additional Information

Confirm Your Distributor Type Before Ordering:

The Sierra 18-5418 fits Delco single-point (conventional) distributors only. Delco distributors were used on GM-sourced marine engines in OMC, Mercury, and Universal applications through the mid-1980s before electronic ignition became standard. To confirm your distributor is a Delco single-point unit:

• Open the distributor cap — a single-point Delco distributor has a rotor mounted on the shaft with a single center contact and a peripheral tip that sweeps past the cap's cylinder terminals
• Cross-reference your current rotor OEM part number against the list above
• If your engine has been converted to electronic ignition (e.g., Thunderbolt, Prestolite, or aftermarket conversion), this rotor will not apply

Mercury Part Number Evolution:

The four Mercury cross-references (58217, 58217Q, 898253008, 8M6001251) represent successive Mercury parts catalog revisions for the same rotor. The 8M6001251 is the current Mercury/Quicksilver catalog number; the earlier numbers may appear in older service manuals or parts diagrams. Any of these Mercury numbers confirms the Sierra 18-5418 is the correct replacement.

Installation Notes:

• Replace the rotor at each tune-up service alongside cap, points (if applicable), and condenser
• Inspect the rotor tip for carbon tracking, cracks, or burned contact — any of these warrant immediate replacement
• Confirm rotor seating fully on the distributor shaft before reinstalling the cap

Frequently Asked Questions

1. How do I confirm this rotor fits my distributor?
Cross-reference your current rotor OEM part number against the list above, or confirm your distributor is a Delco single-point unit for a 4-cylinder or inline 6-cylinder marine engine. If your current rotor is OMC 384735, Mercury 58217 (or any of the Mercury numbers listed), or Universal 288702, the Sierra 18-5418 is the correct replacement.

2. Does this fit electronic ignition distributors?
No — the 18-5418 is for Delco single-point (conventional) distributors only. Electronic ignition systems use a different rotor design. If your engine has been converted to electronic ignition or came factory with electronic ignition, this rotor does not apply.

3. How often should the rotor be replaced?
Replace at each tune-up — typically every 100 hours or annually, whichever comes first. Always replace the rotor together with the distributor cap; installing a new cap on a worn rotor (or vice versa) negates most of the tune-up benefit.