Here's a general outline of the process. However, this is NOT a substitute for a proper repair manual specific to your Isuzu engine and model. Using incorrect timing can severely damage your engine.
Before you begin:
* Consult a Factory Repair Manual: This is absolutely crucial. The manual will have the precise specifications for your engine, including timing marks, procedures, and torque specifications.
* Gather Tools: You'll need a timing light, socket wrench set, possibly a crankshaft pulley holder, and possibly a distributor timing tool depending on your ignition system.
* Safety First: Disconnect the negative battery terminal before starting any work on the ignition system.
General Steps (this is a simplified overview and might not apply directly to your specific engine):
1. Locate Timing Marks: Find the timing marks on the crankshaft pulley and the camshaft (if applicable). Your repair manual will show you their location.
2. Set the Piston to Top Dead Center (TDC): This is usually done on the #1 cylinder. Turn the crankshaft until the piston is at TDC on the compression stroke. Your repair manual will detail how to verify this.
3. Set the Camshaft (if applicable): If your engine has a separate camshaft, align its timing marks with the specified marks on the engine block.
4. Set the Distributor (if applicable): If your engine has a distributor, you'll need to use a timing light to adjust the distributor rotor position to match the timing mark on the engine block. This is where the timing light and repair manual's specified timing advance are crucial. Incorrectly setting the distributor can cause major engine damage.
5. Verify Timing: After setting the timing, recheck your work with the timing light to ensure it's correct.
Important Considerations:
* Electronic Ignition vs. Distributor: The process will differ significantly depending on whether your engine uses an electronic ignition system or a distributor. Electronic systems often require a diagnostic tool for proper timing adjustment.
* Belt or Chain Driven: Knowing if the camshaft is driven by a belt or chain will impact the timing procedure. A timing belt is easier to access than a chain.
* Specific Engine Code: The exact procedure will vary greatly depending on the specific Isuzu engine code (e.g., 4JB1T). The repair manual is the only reliable source of information.
Strongly Recommended:
* If you are not experienced with engine timing, do not attempt this yourself. Incorrect timing can cause catastrophic engine damage.
* Seek professional help from a qualified mechanic. The cost of repairing engine damage caused by incorrect timing will far outweigh the cost of professional service.
In short: Get the repair manual for your *specific* 1985 Isuzu 1.9L engine. This will provide the detailed, step-by-step instructions, diagrams, and specifications you need to time the engine correctly and safely. Attempting this without it is strongly discouraged.
