OEM Champion Spark Plug for Briggs & Stratton 5066, 5066B, 5066K, 594056 OHV Engine

What It Is

This is an OEM factory-replacement Champion spark plug designed specifically for Briggs & Stratton 5066, 5066B, 5066K, and 594056 OHV engines. It’s used in walk-behind mowers, riding mowers, and small utility engines that require a resistor spark plug for reliable ignition.

Fitment & Compatibility

Before buying, verify your engine model number (stamped on the valve cover or blower housing) matches one of these: 5066, 5066B, 5066K, or 594056. This plug replaces Champion RC12YC and equivalent cross-references like Autolite 3923, NGK BPR6ES, or Bosch WR7DC. It has a 14mm thread size, 19mm (3/4") reach, and a gasket seat. Do not use on non-OHV or older L-head Briggs engines unless cross-referenced. Always check the gap (typically 0.030") before installation—do not assume it’s pre-gapped.

Key Things to Know

• Quality: OEM Champion build ensures correct heat range and electrode material for Briggs OHV engines—aftermarket plugs may cause misfires or pre-ignition.
• Installation difficulty: Easy (15 minutes). Requires a 5/8" spark plug socket and a torque wrench (18-20 ft-lbs recommended). Over-tightening can strip aluminum threads.
• Common gotcha: The plug may arrive with a loose gap. Always verify with a feeler gauge—0.030" is standard, but check your engine manual.
• Lifespan: Replace annually or every 100 hours of use. A worn plug causes hard starts, rough idle, and reduced power.

Should You Buy It

If you own one of the listed Briggs & Stratton OHV engines and want a reliable, drop-in replacement that won’t cause starting or performance issues, this OEM plug is a smart buy. It’s especially worth it for DIYers who prefer guaranteed fit and heat range over cheaper generic options. Skip it if your engine model isn’t listed or you’re willing to gap and test an aftermarket cross-reference.