How many amps does a 350 Chevy alternator put out?
In most cases, a 350 Chevy's alternator puts out roughly 60 to 130 amps, depending on the model and whether it's stock or upgraded. Higher-output units reaching 160 amps are common in performance builds.
What determines the amperage output
The exact figure isn’t fixed; alternators are rated by their maximum output at a specified engine speed, and real-world output depends on engine RPM, belt condition, regulator, temperature, and electrical load. If you’re upgrading or diagnosing charging issues, you’ll want to know both the rating and the actual performance under load.
Several factors shape usable current in daily driving, including the alternator's regulator type, the pulley ratio, wiring gauge, age of the belt, and how many electrical devices you’re running at once (air conditioning, headlights, audio systems, etc.).
Typical amperage ranges for 350 Chevy alternators
Below are ranges you commonly encounter in factory-equipment and aftermarket replacements for the small-block Chevy 350. They reflect maximum output under specified conditions, not the idle or surge current you’ll see at low RPMs.
- 60–78 amps (early OEM or low-output variants)
- 78–105 amps (mid-era OEM or widely used aftermarket replacements)
- 120–160 amps (modern high-output replacements for street and performance use)
- 180–200+ amps (extreme high-output setups for very heavy electrical demand)
These ranges help you plan charging capacity and compatibility with your electrical load. Always check the exact rating printed on the alternator or in the product specs when shopping or upgrading.
How to identify the amperage on your alternator
Look for a stamped rating or a metal label on the alternator housing. The amp rating is usually listed (for example 105A, 120A, etc.). If the label is missing, check the service manual for your model year or the replacement part’s specs.
Measuring actual output under operating conditions
To verify real-world performance, measure the system current while the engine is running with accessories on. Use a clamp-on ammeter around the primary charging cable and monitor the charging voltage with a digital multimeter; aim for about 13.5–14.8 volts when the alternator is charging.
Upgrade considerations for higher output
When moving to a higher-output unit, ensure compatibility with your engine, mounting, regulator type (internal vs external), and wiring. Higher-output alternators may require changes to wiring gauge, fuses, and sometimes a different regulator or pulley setup to achieve the rated output without overheating.
- 120–135A class replacements are common upgrades for many street builds
- 140–160A units are popular for cars with substantial electrical loads (performance audio, heavy air conditioning)
- 180–200A units are used in specialized builds with very high electrical demand
Before purchasing, verify fitment, regulator compatibility, and wiring needs, and consider whether a one-wire or three-wire configuration is appropriate for your swap or restoration.
Summary
The amperage a 350 Chevy alternator puts out isn’t fixed; it ranges from about 60A in older, low-output units to 130A or more in modern replacements, with high-output models exceeding 160A for heavy electrical loads. Your best approach is to match the alternator rating to your expected electrical demand, verify with actual load testing, and ensure wiring and mounting support the chosen unit.
