Here's a breakdown of how to approach it, but I strongly recommend consulting a repair manual specific to your year and engine. The procedure varies significantly depending on whether you have a distributor-based ignition system or a more modern computer-controlled system.
1. Identify Your Ignition System:
* Distributor Ignition (Older Roadmasters): This involves a distributor cap, rotor, and points (older models) or an electronic ignition module (slightly newer models). Timing adjustment is done mechanically at the distributor.
* Computer-Controlled Ignition (Newer Roadmasters): The timing is controlled by the Engine Control Module (ECM). You can't adjust it manually; you'll need a scan tool to read and possibly adjust timing parameters. Often, if the timing is "off" it points to a sensor problem or other ECM issue.
2. Gather Tools and Materials (For Distributor Ignition):
* Repair manual: Absolutely essential for your specific year and engine.
* Timing light: This is crucial for accurately setting the timing.
* Socket wrench set: For removing and installing parts.
* Wrench to adjust the distributor: Usually a socket or wrench.
* Safety glasses: Protect your eyes from flying debris.
* Gloves: Keep your hands clean and protect them from grease.
3. Procedure (Distributor Ignition - General Steps):
* Consult your repair manual: This is NOT optional. The specifics (marks on the harmonic balancer, distributor adjustment procedures, etc.) are crucial and vary by model year and engine.
* Locate the timing marks: These are usually on the harmonic balancer (a pulley on the crankshaft) and the engine block.
* Connect the timing light: Clamp the timing light to a high-voltage wire and connect its power clamp to a good ground.
* Start the engine: The timing light will illuminate the timing marks on the balancer.
* Compare the timing mark position to the specified timing setting in your repair manual: This is usually expressed in degrees Before Top Dead Center (BTDC).
* Adjust the distributor: Loosely loosen the distributor mounting clamp. Rotate the distributor slightly to adjust the timing mark to the specified setting. Tighten the clamp.
* Recheck the timing: Restart the engine and verify the timing is correct.
4. Procedure (Computer-Controlled Ignition):
* Use a scan tool: You'll need an OBD-II scan tool (or a more advanced tool depending on the year) to read the timing advance.
* Diagnose the problem: If the timing is off, the problem is unlikely to be a simple adjustment. Possible causes include faulty sensors (crankshaft position sensor, camshaft position sensor), a failing ECM, or even a problem within the engine's mechanical components.
* Professional help is usually needed: Unless you're very experienced with automotive diagnostics and repair, tackling this is best left to a qualified mechanic.
Important Safety Considerations:
* Disconnect the negative battery cable before working on the ignition system.
* Be careful around moving parts when the engine is running.
* Only work on the car in a well-ventilated area. Carbon monoxide is deadly.
In summary: Adjusting the timing, especially on an older Roadmaster, requires mechanical skill and a specific repair manual. If you're uncomfortable with this, take it to a qualified mechanic. Improperly setting the timing can cause serious engine damage.
