Briggs & Stratton 397358 Magneto Armature for 5 HP Engines — OEM direct-fit, restores reliable spark

The Briggs & Stratton 397358 magneto armature is an OEM ignition armature designed to restore reliable spark and correct fit on select 5 HP horizontal and vertical shaft and 550 series engines.

If your small engine is misfiring, hard to start, or showing intermittent ignition problems, replacing the magneto armature with a genuine Briggs & Stratton part can return factory tolerances and help maintain engine longevity. This replacement armature matches the original specifications so installation is straightforward on compatible models and it helps ensure consistent spark timing and coil clearance.

Which engines is the 397358 magneto armature compatible with?

This armature is manufactured for select Briggs & Stratton 5 horsepower engines with both horizontal and vertical shafts, and for certain 550 series models. Always compare part numbers and engine serial/model information to confirm compatibility before ordering.

• Designed for select 5 HP horizontal-shaft engines
• Fits select 5 HP vertical-shaft engines
• Compatible with specified 550 series engines
• Genuine OEM part number 397358 for accurate replacement

How does this armature improve ignition performance?

Replacing a worn or damaged armature restores the magnetic field strength and corrects air-gap alignment with the ignition coil, which helps produce a consistent and strong spark. That steadier ignition reduces misfires and makes starting easier under a variety of conditions.

• Reestablishes proper magnetic flux for reliable spark generation
• Restores factory air-gap tolerances for consistent timing
• Reduces intermittent spark and misfire events
• Helps the coil produce a stronger secondary spark

What should I expect when installing the 397358 armature?

Installation is a direct replacement when used on compatible Briggs & Stratton engines: remove the flywheel/old armature per service manual steps, index the new armature correctly, and set the specified air gap. If you’re unfamiliar with small-engine ignition work, follow the engine’s service manual or consult a technician to avoid timing errors.

• Direct-fit OEM replacement—no machining required
• Install per engine service manual instructions
• Requires correct air-gap setting for optimal function
• Torque and timing checks recommended after install

What are the part dimensions and packaging details?

The replacement armature ships in compact packaging sized approximately 2-3/4" L x 3-1/2" W x 4" H, making it easy to store until you’re ready to install. The compact package contains the armature built to OEM tolerances so it fits and functions like the original component.

• Package dimensions: 2-3/4" x 3-1/2" x 4"
• OEM-manufactured armature for dimensional accuracy
• Shipped ready for direct replacement installation
• Part number: Briggs & Stratton 397358

Who is this for: The Briggs & Stratton 397358 magneto armature is intended for homeowners, landscapers, and small-engine technicians who maintain or repair lawn mowers, generators, and other outdoor power equipment powered by compatible Briggs & Stratton engines. Choose this OEM armature when you want a like-for-like replacement that preserves factory fit and ignition performance.