Engine Technology Time the Ignition Some service procedures require removing the distributor from the engine. If the crankshaft is turned, the proper relationship must be reestablish between the distributor and engine timing (piston position) and normally engines are time on piston # 1 Introduction Timing the Distributor to the Engine 1. Locate the cylinder # 1 in firing order (compression stroke). - Remove the number 1 spark plug (to ensure piston at TDC) - Locate the timing marks where a rotating mark that aligns with a specified stationary mark when ignition timing is correct. - This show the cylinder # 1 in firing position. - Usually on the crankshaft vibration damper and the engine front cover. Some are on the flywheel and the housing.

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Time the Ignition 2. Turn the distributor rotor tip pointing to # 1 terminal in the distributor cap. 3. Install the distributor, making sure the rotor tip aligns with the cap terminal for the number 1 spark plug. 4. Hold the cap in its mounting position above the distributor. Check that the rotor tip aligns with the number 1 terminal on the cap. 5. Install the cap. Connect all the spark plugs cable. 6. Start the engine and set the ignition timing with timing light. 7. Tighten the mounting bolt and connect all the vacuum hoses.

Engine Technology Time the Ignition Setting the Ignition Timing The engine requires two types of ignition timing. 1.Basic or initial timing for starting and idling – determined by the relationship between piston position and the opening of the primary circuit. 2.Spark advance – advances and retards the spark from the basic timing setting, primarily as engine speed and load change. It is mechanically controlled by centrifugal and vacuum advance mechanisms. Electronic spark advance is used on many electronic distributors and in all distributorless ignition systems. Once the timing is set, electronic ignition systems normally do not require periodic timing adjustments most engines with a distributor, this is performed by turning the distributor slightly. Some engines have a distributor that mounts in a fixed position. The timing may be adjusted by installing a different reluctor

Engine Technology Time the Ignition Procedure to check and set the timing 1.Engine at normal operating temperature and idling at the specified speed 2.Eliminate all spark advance mechanical and electronic, so the engine is running on only basic timing by: The low engine speed prevents spark advance from the centrifugal advance mechanism in the distributor. Removing the vacuum hose from the vacuum-advance unit disables the vacuum advance. Plug the hose to prevent air leak into the intake manifold. Follow the procedure on the VECI label to disable electronic spark advance. This may include opening a set timing connector or disconnecting the SPOUT connector.

Engine Technology Time the Ignition 3.Turning the distributor in its mounting to adjust the basic timing: Rotating the distributor in the direction opposite to rotor rotation advances the timing. This opens the primary circuit earlier. Turning the distributor in the same direction as rotor rotation retards the timing. The spark occurs later. Determining when the timing is properly adjusted requires the use of timing light or a magnetic timing tester. On many vehicles, initial timing and spark advance can be read from a scan tool, computerized engine analyzer, and service bay diagnostic computer

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