Here's a general overview of the process. Specific details may vary slightly depending on the year, model, and modifications of your 350. Always consult your engine's specific specifications and a reputable repair manual for precise instructions.
Tools You'll Need:
* Timing light: Essential for accurately setting the timing.
* Socket set and wrenches: For removing and adjusting components.
* Distributor wrench: To rotate the distributor.
* Spark plug socket: To disconnect spark plug wires.
* Chilton's or Haynes repair manual: A specific manual for your year and model 350 is highly recommended.
* Safety Glasses & Gloves: Always protect yourself!
Steps:
1. Safety First: Disconnect the negative battery cable.
2. Locate Timing Marks: Find the timing marks on the crankshaft damper (harmonic balancer) and the timing chain cover (or timing pointer on the block). The crankshaft damper will have markings (often 0° and other degree markings). The timing cover (or pointer) will typically have a corresponding mark indicating Top Dead Center (TDC) on the #1 cylinder compression stroke.
3. Verify Top Dead Center (TDC) of #1 Cylinder: With the #1 spark plug removed, carefully rotate the crankshaft using a wrench on the harmonic balancer bolt until the piston in the #1 cylinder reaches TDC on the compression stroke (both valves closed). Verify this using a piston stop or by feeling air pressure through the spark plug hole.
4. Set the Distributor: Loosen the distributor hold-down clamp. Rotate the distributor to roughly align the rotor with the #1 spark plug wire tower. This is an approximation; fine-tuning will happen later.
5. Reconnect the Spark Plug Wires: Ensure that the spark plug wires are correctly connected to the distributor cap in the proper firing order (typically 1-8-4-3-6-5-7-2, but check your engine's specifications).
6. Connect the Timing Light: Connect the timing light's inductive clamp around the #1 spark plug wire. Connect the timing light to a 12V power source.
7. Start the Engine: Have a helper crank the engine while you aim the timing light at the timing marks on the crankshaft damper. The timing light will illuminate the marks, showing the actual ignition timing.
8. Adjust the Timing: Compare the illuminated timing mark with the desired timing specification (found in your repair manual; this is usually around 8-12 degrees BTDC (Before Top Dead Center) at idle for a stock engine, but can vary significantly). Use the distributor wrench to carefully adjust the distributor's position, increasing or decreasing the timing until it matches the specification.
9. Recheck the Timing: After adjusting, recheck the timing several times to ensure it's stable.
10. Reconnect Battery: Once you're satisfied with the timing, reconnect the negative battery cable.
Important Considerations:
* Vacuum Advance: The vacuum advance on the distributor can affect the timing. Many manuals will recommend disconnecting it while setting the initial timing.
* Mechanical Advance: The mechanical advance in the distributor also plays a crucial role. Don't try to adjust this unless you're experienced with distributors.
* Engine Modifications: If you have performance modifications (camshaft, headers, etc.), the optimal timing will likely be different than stock. Consult a performance manual or tuner for guidance.
* Initial vs. Total Timing: The timing you adjust is the *initial* timing at idle. The total timing includes the mechanical and vacuum advances.
Again, this is a simplified overview. Refer to a repair manual specific to your 350 engine for detailed instructions and safety precautions. Improper timing can cause serious engine damage, so proceed with caution. If you are unsure about any step, seek help from a qualified mechanic.
