What should a Chevy 350 timing be set at?
In most street Chevy 350 builds, you’ll want an initial timing around 6–8 degrees BTDC and a total timing around 32–34 degrees BTDC once the engine is warmed up. The exact numbers depend on year, camshaft, compression, and fuel, so check the factory specs for your specific engine and verify with a timing light.
Timing determines when the spark occurs in the compression stroke, influencing idle quality, throttle response, and detonation resistance. The right setup varies with stock versus performance configurations, so start with conservative targets and adjust based on how the engine runs and sounds under load.
Typical timing targets for a Chevy 350
These targets assume a stock ignition system or a similar aftermarket distributor, with the engine warmed and idling. Use a timing light to confirm both the initial and total timing against the engine’s manual spec.
- Initial timing (BTDC): about 6–10 degrees; many builders start around 8 degrees for a mild street engine.
- Total timing (BTDC): about 32–36 degrees; a common target is 34 degrees for a stock-to-mildly modified engine running regular octane fuel.
- Vacuum advance: when connected, vacuum canister adds timing at light load; the overall timing should remain within the 32–36 degree band.
These figures are guidelines. If you have a higher-compression build or a performance cam, you may run toward the upper end (34–36 degrees total). If you’re using lower-octane fuel or experiencing detonation, back off initial timing and/or total timing accordingly. Always verify with a timing light after any adjustment.
How to set timing on a Chevy 350
Follow these steps to set both initial and total timing, ensuring the vacuum advance is properly managed.
- Warm the engine to operating temperature (about 180–200°F / 82–93°C).
- Disconnect the vacuum advance hose from the distributor and cap the hose to prevent leaks.
- Attach a timing light to the number-one cylinder spark plug wire and point the light at the timing tab. Loosen the distributor hold-down bolt just enough to allow rotation.
- With the vacuum line disconnected, rotate the distributor to set the initial timing to the desired value (commonly around 8 degrees BTDC) at idle in park/neutral.
- Reconnect the vacuum advance hose. Confirm the port type (ported or full vacuum) matches the factory spec and the canister is functioning properly.
- With the engine idling, observe the total timing. If required, adjust the distributor to bring total timing to the target (usually 32–34 degrees) by rotating while watching the timing mark with the timing light.
- Take the car for a test drive to check for detonation or ping under load; if ping occurs, reduce timing slightly. If response is sluggish, you may be able to advance a few degrees within safe limits and re-test.
Once an optimum timing setup is found, re-torque the distributor and re-check all connections. If your engine uses a high-performance cam or high compression, a custom tune or dyno verification may be warranted.
Summary
For a typical Chevy 350, aim for an initial timing around 6–8 degrees BTDC and a total timing around 32–34 degrees BTDC once warm. These targets can shift with cam choice, compression, and fuel; always consult the factory manual for your exact year and configuration and verify with a timing light on a warm engine. Proper timing improves performance, efficiency, and engine safety.
