Description

When your tractor or implement’s engine starts running rough, misfiring, or getting hard to start, there’s a good chance it’s time for fresh spark plugs. This Autolite 303 is a reliable medium heat range plug that’ll get your smaller engines firing strong again. With its resistor design, it cuts down on radio frequency interference—something you’ll appreciate if you’re running GPS guidance or a two-way radio in the cab.

What You’re Getting

Medium heat range works well in most operating conditions without fouling or overheating
Built-in resistor reduces electrical interference with onboard electronics
Standard 14mm thread with 3/8 inch reach fits a wide range of small engines
Proven design that mechanics have trusted for decades
Direct replacement for Champion J5, J6, J6C, J6J, RJ6, RJ6C, UJ6, J7, J7J, and RJ7 plugs

Built for Real Farm Work

This plug is designed for the smaller engines you’ll find throughout the farm—think tractor-mounted generators, irrigation pump engines, compact utility tractors, and various implements with their own power units. These engines work hard in dusty conditions and need a plug that can handle the job without constant replacement.

Made to Last

The medium heat range strikes the right balance for most farm applications. It runs hot enough to burn off carbon deposits but cool enough to avoid pre-ignition problems. The resistor element is built into the center electrode, so it won’t come loose or cause problems down the road.

Good to Know

Always gap new plugs to your engine’s specifications before installing—don’t assume they come pre-gapped correctly. When you’re swapping plugs, it’s a good time to check the ignition wires and clean any corrosion from the plug boots. If you’re replacing just one plug in a multi-cylinder engine, consider doing them all at once to keep everything running smooth.