Here's a general overview. Specific procedures may vary slightly depending on your particular engine and year. Always consult your vehicle's service manual for the most accurate and detailed instructions.
Tools You'll Need:
* Timing light: Essential for accurately setting the timing.
* Socket set: To access distributor and other components.
* Wrench set: For various fasteners.
* Spark plug wires: If you need to remove the distributor cap. Label them carefully before removal.
* Owners manual or repair manual: To find the correct specifications for your engine.
Steps:
1. Safety First: Disconnect the negative battery terminal.
2. Locate Timing Marks: The timing marks are usually found on the harmonic balancer (the pulley on the crankshaft) and the timing cover. The timing cover might have a pointer. You need to be able to see both when the engine is running.
3. Find Top Dead Center (TDC) on #1 Cylinder: With the distributor rotor pointing at the #1 spark plug wire terminal on the distributor cap, rotate the engine (by hand using a socket wrench on the crankshaft bolt) until the timing marks align at 0 degrees. Double-check your work!
4. Connect the Timing Light: Clamp the timing light's inductive clamp around the #1 spark plug wire. Point the timing light at the timing marks on the harmonic balancer and the timing pointer.
5. Start the Engine: Have a helper crank the engine while you observe the timing marks through the timing light. The illuminated marks should show the current timing advance.
6. Adjust the Timing: The initial timing setting is usually specified in your vehicle's service manual (it's typically between 6 and 10 degrees BTDC (Before Top Dead Center)). This is usually achieved by loosening the distributor clamp bolt and rotating the distributor. Rotate the distributor clockwise to advance the timing and counter-clockwise to retard it.
7. Fine-Tune: Make small adjustments (1-2 degrees at a time) and check the timing mark through the timing light until it matches the specified initial timing.
8. Reconnect Battery Terminal: After setting the timing, reconnect the negative battery terminal.
Important Considerations:
* Vacuum Advance: Many 350 Chevy engines have a vacuum advance mechanism on the distributor. This automatically adjusts the timing based on engine load and vacuum. You might need to disconnect the vacuum advance line to set the initial timing accurately. Your service manual will tell you how to handle this.
* Mechanical Advance: Your distributor also has a mechanical advance mechanism. This is internal to the distributor and usually isn't adjusted.
* Engine RPM: The timing is usually set at idle speed.
* Dwell: Setting the dwell is important for consistent ignition. If your ignition system has dwell issues, the timing will be erratic and unreliable. A dwell meter is needed to check and adjust dwell.
Again, this is a general overview. Incorrectly setting the timing can cause serious engine damage. Consult your service manual and if you're unsure, seek professional help. Using the wrong information can damage your engine. Always verify procedures with a reputable source for your specific engine and year.
