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Description:
The Champion Copper Plus RN5C Spark Plug is engineered to provide dependable ignition performance, reliable heat control, and long service life. Built with a copper core center electrode, this plug delivers strong conductivity and accurate heat range control to help reduce wear and support consistent combustion.
As part of the Champion Copper Plus Small Engine line, the RN5C is designed as an OE-type replacement plug for a wide range of compatible engines. Its resistor design helps suppress ignition interference for smoother operation, while the corrosion-resistant construction supports durability in demanding use. Manufactured to ISO and SAE standards, it offers proven performance and fit for automotive, small engine, and specialty applications.
With a flat seat, crush washer, and removable nut terminal, the RN5C is a dependable replacement choice for engines requiring a gasket-seat spark plug.
Features:
Copper Plus design for dependable performance and durability
OE-type replacement spark plug
Copper core center electrode improves conductivity and heat control
Resists fouling for reliable ignition performance
Corrosion-resistant construction for longer service life
Resistor design helps reduce ignition interference
Built to ISO and SAE standards for proven performance
Flat seat with crush washer for secure installation
Product Specifications:
Part number: 123
Plug type: RN5C
Classification: Champion Copper Plus Small Engine
Grade type: Standard Replacement
Part description: Spark Plug
Center electrode tip material: Copper
Center electrode design: Standard
Center electrode diameter: 0.1 in
Ground electrode material: Nickel copper alloy
Ground electrode core material: Nickel
Ground electrode tip material: Nickel
Ground electrode quantity: 1
Pre-gap size: 0.025 in / 0.64 mm
Hex size: 0.813 in / 20.650 mm
Seat type: Flat
Reach: 0.75 in
Thread diameter: 0.551 in / 14.000 mm
Resistor type: Yes
Washer included: Yes
Washer type: Crush
Electrical terminal type: Removable Nut
Manufacturer heat range: 5
Indexed: No
Hex type: Hex
Installed height: 2.24 in
Taper diameter: 0.25 in
Subject to Prop 65: No
Fitment:
The supplied application list shows broad fitment across many classic automotive and specialty applications, including select models from:
Alfa Romeo, Allard, Alvis, Armstrong-Siddeley, Arnolt-MG, Austin, Austin Healey
BMW, Bentley, Berkeley, Bugatti
Chevrolet
Dodge
Elva
Fargo
GMC
Healey, Hillman, Honda, Humber
International
Jaguar, Jensen
Lamborghini, Lanchester, Lancia, Land Rover, Lotus
MG, Metropolitan, Morgan, Morris
NSU, Nissan
Porsche
Renault, Riley, Rolls-Royce, Rover
Singer, Standard, Sunbeam
TVR, Triumph
Vauxhall, Volkswagen
Wolseley
Order Processing
All orders are processed and shipped within 24 hours of purchase (excluding weekends and holidays).
Orders placed after 3:00 PM EST may ship the following business day.
Shipping Methods
Customers select their preferred shipping method and speed at checkout.
Shipping times are determined by the carrier and cannot be guaranteed by us.
Tracking information will be provided once your order has shipped.
Shipping Coverage
If your package arrives damaged, please notify the delivery driver immediately and contact the shipping carrier to file a claim.
You must report any missing or damaged items within 14 days of delivery.
After this time, we cannot be held responsible for lost or damaged items.
Return Window
You have 30 days from the date of delivery to request a return.
After 30 days, we are unable to accept returns, exchanges, or refund requests.
Eligibility
Items must be returned in their original condition—unused, unwashed, and with all tags and packaging intact.
Certain products may not be eligible for return (e.g., special-order items, customized products, or perishable goods).
Items that have been altered, installed, or modified cannot be returned.
Return Process
Contact our Customer Support team to request a Return Authorization (RMA) before sending items back.
Once your return is approved, you’ll receive instructions on where to send the product.
Customers are responsible for return shipping costs unless the item was defective or incorrect.
Refunds
Refunds are issued to the original payment method once the returned item has been received and inspected.
Please allow 5–10 business days for the refund to appear on your account.
In some cases, a restocking fee may apply (if applicable, this will be disclosed during your return authorization).
