Autolite AP26 Spark Plug

Platinum spark plug replacement

Autolite AP26 is a platinum spark plug built for OE-style form, fit, and function across a wide range of classic domestic applications. It uses platinum on the center electrode and a nickel ground electrode to support durable ignition performance and consistent service life.

• Platinum center electrode for improved durability versus standard copper plugs
• Tapered ground electrode tip design for stable spark delivery
• Mid-projection ceramic insulator for controlled combustion chamber placement
• Resistor design with 4000 resistance rating
• Pre-gapped to 0.045 in. / 1.10 mm

Product details

Autolite AP26 is a direct OE-style spark plug replacement for many Chevrolet, Ford, and GMC applications, including Chevrolet Camaro, Ford Mustang, and GMC Jimmy listings in the fitment data. The plug features a 14 mm thread diameter, 5/8 in. hex, tapered seat, stud terminal, and 0.433 in. reach, making it a fitment-specific ignition component for engines that call for this configuration. Autolite AP26 is also cross-referenced to Autolite 25 and DENSO 5020 for the same application.

Autolite’s Platinum Spark Plug line focuses on durable electrode construction and OE-type replacement geometry. For buyers searching for an Autolite AP26 spark plug for Chevrolet Camaro, Ford Mustang, or GMC Jimmy applications, this part is positioned as a value-oriented replacement that follows the required gap and terminal style called out in the fitment data.

Common issues this part can address

• Hard starting caused by worn spark plug electrodes
• Rough idle from inconsistent ignition firing
• Reduced throttle response from degraded spark delivery
• Maintenance intervals shortened by standard copper plug wear
• Misfire concerns when the existing plug no longer matches the specified gap

Installation notes and tips

Verify the engine’s required spark plug gap before installation and confirm the specified seat type, reach, and terminal style match the vehicle application. The fitment data lists multiple gap specifications by vehicle, so use the application notes for the exact setting. Install AP26 only in engines that call for this plug configuration, and torque to the vehicle manufacturer’s specification.

Quality assurance

Autolite supplies spark plugs to the automotive aftermarket and original equipment manufacturers and positions this Platinum Spark Plug line as an OE-style replacement option. AP26 is built to support durable ignition performance with platinum electrode materials and application-specific fitment data.