RPS Tune Up Kit for MerCruiser & OMC 2.5L–3.7L Engines — Distributor Cap, Rotor & Wires

RPS Tune Up Kit replaces the entire points-style ignition assembly for MerCruiser and OMC 2.5L, 3.0L and 3.7L 4-cylinder engines (1963–1989) with a new distributor cap, rotor, points, condenser and marine spark plug wires.

Here is a complete, drop-in ignition service kit engineered to restore spark delivery and timing stability on classic MerCruiser and OMC 4-cylinder engines that use Delco conventional (points) ignition. The kit bundles the heavy-duty distributor cap with brass terminals, a matched rotor, contact points, condenser, a .020 metal spacer and marine-grade spark plug wires so you can replace every wear item that affects misfires, rough idle and poor starts. RPS designed the components for seaworthy durability and direct interchange with original Mercury/MerCruiser and OMC part numbers, making this a practical choice for restorations, preventive maintenance, or getting an older rig back to reliable operation.

What components are included and why are they paired together?

The kit contains all the friction and electrical wear parts of a conventional points ignition: distributor cap, rotor, contact points, condenser, spark plug wires and a .020 metal spacer. These items are grouped to address both mechanical timing and electrical conductivity at once.

• Distributor cap with heavy-duty brass terminals for corrosion resistance and improved conductivity.
• Matched rotor to ensure consistent contact timing and reduced arcing.
• Contact points and condenser to restore mechanical dwell and suppress electrical noise.
• Marine-grade spark plug wires sized for 4-cylinder routing and high dielectric strength.
• .020 metal spacer to achieve correct point gap and timing where needed.

How does this kit help reduce misfires and improve starting?

Replacing worn cap, rotor and wires eliminates common failure points that cause weak or erratic sparks. New components restore voltage transfer and consistent contact timing so the spark plugs fire reliably, improving cold starts and steady idling.

• New brass terminals reduce pitting and improve long-term contact quality versus aluminum.
• High-dielectric wires reduce leakage and preserve available voltage at plugs.
• Fresh points and condenser restore correct dwell and prevent timing drift.
• Comprehensive replacement removes guesswork—no scavenged parts.

Will this kit fit my engine and replace OEM part numbers?

This RPS tune up kit is engineered for 1963–1989 MerCruiser and OMC 4-cylinder engines that use Delco conventional (points) ignition, including 2.5L, 3.0L and 3.7L variants. It directly replaces several Mercury/MerCruiser and OMC part numbers for a straightforward swap.

• Compatible with 2.5L (120 hp), 3.0L (140 hp), and 3.7L (165–190 hp / 470 series) 4-cylinder engines.
• Cross-references include Mercury/MerCruiser 393-9459Q1, 393-9459T, 33667, 84-816761Q5 and OMC 380541 among others.
• Aftermarket interchange with Sierra 18-5385 and GLM 71540 for broader sourcing.
• Designed for direct, no-modification installation where original points-style systems are present.

How durable are the parts for marine environments?

Components are selected with saltwater and humidity exposure in mind. Brass cap terminals, marine-grade wire construction and corrosion-conscious materials help extend service life compared with standard automotive replacements.

• Heavy-duty brass terminals resist electrochemical corrosion in damp environments.
• Spark plug wires feature high dielectric insulation to limit leakage and arcing.
• Condenser and hardware use robust finishes to reduce premature failure.
• Built and tested by RPS to meet routine marine service demands.

Who is this for: The RPS Tune Up Kit is intended for boat owners, marine mechanics and classic MerCruiser/OMC restoration projects that still use Delco points-style ignition. It’s the right choice when you want a single, reliable parts package to replace every ignition wear item—ideal for preventative maintenance, eliminating intermittent ignition problems, or returning a vintage 4-cylinder stern or outboard-powered boat to dependable operation. If your engine currently uses electronic ignition or distributorless systems, this kit is not applicable; verify your distributor style before ordering.