1. Identify the Ignition System:
* Distributor Ignition: A 1995 Silverado 350 likely has a distributor-based ignition system. This is the more traditional method with a distributor cap, rotor, and ignition coil.
* Coil-Near-Plug (CNP) or Coil-on-Plug (COP): While less likely on a '95, some late-model year trucks may have started using a more modern system. If it's a CNP or COP system, the timing is controlled by the engine control module (ECM) and is not adjustable in the same way as a distributor system.
2. Gather Your Tools:
* Timing Light: Essential for seeing the timing mark.
* Socket Set and Wrenches: For accessing and adjusting the distributor.
* Shop Manual: A factory service manual for your specific year and engine is invaluable. It will have the exact specifications and procedures for your truck.
* Spark Plug Wrench: Might be needed to check spark plug condition.
* Safety Glasses and Gloves: Protect yourself from potential hazards.
3. Preparation (Distributor Ignition System):
* Locate Timing Marks: Consult your shop manual to find the timing marks on the harmonic balancer (pulley) and the timing pointer on the engine block.
* Find the Distributor Hold-Down Clamp: You'll need to loosen this to adjust the distributor.
* Disconnect Negative Battery Terminal: This is crucial for safety.
* Warm Up Engine: The engine should be at normal operating temperature, as timing can vary slightly with temperature. Consult the manual for specifics.
4. Timing Procedure (Distributor Ignition System):
1. Connect the Timing Light: Clamp the timing light to a high-voltage spark plug wire, making sure the timing light's clamp is securely attached.
2. Connect the Timing Light to the Battery: Connect the timing light's power leads to the battery.
3. Find Idle Speed: Let the engine idle.
4. Shine the Timing Light: Point the timing light at the timing marks on the harmonic balancer. The light will flash, illuminating the timing mark.
5. Check Timing: Compare the illuminated mark on the balancer to the timing pointer on the engine block. Your shop manual will specify the correct timing degrees (e.g., 0-10 degrees BTDC – Before Top Dead Center).
6. Adjust Timing (If Necessary): If the timing is off, carefully loosen the distributor hold-down clamp. Rotate the distributor slightly to adjust the timing. Check your timing again after each small adjustment. Rotate the distributor clockwise to advance the timing and counter-clockwise to retard it.
7. Tighten Hold-Down Clamp: Once the timing is correct, tighten the distributor hold-down clamp.
8. Double-Check Timing: Recheck the timing to ensure it remains correct.
5. Post-Timing:
* Reconnect Battery Terminal: Reconnect the negative battery terminal.
* Test Drive: Take the truck for a test drive to ensure it runs smoothly.
If your truck has a CNP or COP system: The timing is controlled by the ECM and isn't adjustable manually. If you suspect a timing issue, you'll need a diagnostic scanner to read codes and check sensor data from the ECM. A professional mechanic will have the tools and knowledge to diagnose problems.
Disclaimer: This information is for general guidance only. Always consult your vehicle's repair manual for the specific procedure and specifications for your 1995 Chevy Silverado 350. Incorrect timing can damage your engine. If you are uncomfortable performing this task, seek the assistance of a qualified mechanic.
