Briggs & Stratton carburetor 591378 for 20 cu. in. horizontal OHV engines — OEM exact-fit, restores fuel delivery

The Briggs & Stratton 591378 is a genuine OEM carburetor designed to replace worn or damaged units on select 20 cu. in. single-cylinder horizontal OHV Briggs & Stratton engines.

If your small engine is running rough, stalling, or using too much fuel, the carburetor is often the culprit. The 591378 is made by Briggs & Stratton to match factory specifications and restore consistent fuel and air delivery. Because it’s an exact-fit OEM part, installation is straightforward for DIYers and service technicians, and it avoids compatibility headaches that can accompany aftermarket alternatives.

Which engines and part numbers does this replace?

This carburetor is specified for select 20 cu. in. horizontal overhead valve Briggs & Stratton single-cylinder engines. It directly replaces a range of older or superseded factory numbers so you can cross-reference service parts lists quickly.

• Compatible with certain 20 cu. in. horizontal OHV single-cylinder engines
• Replaces Briggs part numbers including 796321, 696132, 696133 and others
• Designed to meet original factory fit, form, and mounting locations

How easy is installation and what should I expect?

Installation typically requires basic hand tools and moderate mechanical skill. Because this is an OEM component, bolt holes, linkages, and fuel inlets line up with the factory mounting points, reducing the need for modification.

• Fits existing mounting studs and throttle linkage points
• Fuel inlet and choke locations match original equipment
• Gaskets and small hardware may be reused if in good condition, but replacement is recommended

What performance improvements will I see after fitting the 591378?

Replacing a degraded carburetor restores the engine’s ability to mix air and fuel at correct ratios, which improves idle stability, throttle response, and starting reliability. While not a performance booster beyond factory spec, it returns the engine to intended operation and efficiency.

• Smoother idle and more consistent revs under load
• Improved starting and fewer stalls during operation
• Reduced rough running and excess fuel consumption when adjusted properly

What should I check before buying this part?

Confirm your engine model and serial number and compare them to parts lists or the original carburetor stamping. Also inspect mounting orientation, throttle linkage type, and fuel connection to ensure the 591378 is the correct replacement.

• Verify engine displacement is 20 cu. in. and it’s a horizontal OHV single-cylinder
• Cross-reference original part number or consult your service manual
• Check choke and throttle linkage compatibility before purchase

Who is this for: The Briggs & Stratton 591378 carburetor is ideal for homeowners, landscapers, and small-engine mechanics who need a reliable OEM replacement for select 20 cu. in. Briggs & Stratton engines. It’s suited to anyone restoring an aging mower, pressure washer, or similar equipment to factory operating condition without the uncertainty of universal aftermarket parts.