ACDelco Spark Plug R45NSX (GM Part #5613566)

Description:

🔧 Part Overview

• Part Number: R45NSX

• GM Part Number: 5613566

• Type: Copper core resistor spark plug

• Thread Size: 14mm x 1.25mm

• Seat Type: Tapered

• Reach: Approx. 19mm (0.75")

• Hex Size: 5/8"

• Terminal: Fixed

• Electrode Material: Copper core with nickel alloy ground electrode

• Special Feature: Often features a green ring on NOS variants, indicating extended tip or premium design

• Country of Origin: Typically marked “Made in USA”

🚗 Specific Applications

The R45NSX plug was commonly used in:

• 1970s–1980s GM vehicles including Chevrolet, Pontiac, Oldsmobile, Buick, and Cadillac

• Small-block and big-block V8 engines (305, 350, 400, 454 CI)

• Marine engines (MerCruiser, OMC, Volvo Penta)

• Industrial and agricultural engines

• Classic hot rods and performance builds using 14mm tapered seat heads