NOS AC RBL15Y4 Spark Plug – GM #5613877

Description:

🔧 Part Overview

• ACDelco Part Number: RBL15Y4

• GM Part Number: 5613877 (commonly associated in GM catalogs)

• Type: Resistor copper spark plug

• Thread Size: 14mm x 1.25mm

• Seat Type: Gasket

• Reach: Approx. 19mm (0.75")

• Hex Size: 13/16"

• Terminal: Fixed

• Electrode Material: Copper core with nickel alloy ground electrode

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

🚗 Specific Applications

The RBL15Y4 plug was commonly used in:

• 1970s–1980s GM vehicles, including:

  • Chevrolet Camaro, Chevelle, Nova, Monte Carlo

  • Pontiac Firebird, Grand Prix

  • Oldsmobile Cutlass, 442

  • Buick Regal, Skylark

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

• Marine engines (MerCruiser, OMC)

• Industrial and agricultural engines

• Classic hot rods and performance builds using 14mm gasketed heads