The contact point set, also known simply as points, is a component found in traditional ignition systems of internal combustion engines. Its primary purpose is to control the timing of the ignition spark, which is crucial for the combustion process in each cylinder. Here are the key purposes of a contact point set:

1. Timing Control:

   • The contact points control the precise timing of the ignition spark. They determine when the spark plug fires, initiating the combustion process in the engine cylinder. Proper timing ensures optimal engine performance, efficiency, and power delivery.

2. Opening and Closing Circuit:

   • The contact points are part of a circuit that includes the ignition coil. When the points are closed, current flows through the primary winding of the ignition coil. When the points open, the magnetic field collapses, inducing a high-voltage spark in the secondary winding of the ignition coil.

3. Regulating Dwell Time:

   • Dwell time refers to the duration during which the contact points are closed. The points must remain closed long enough for the ignition coil's primary winding to build up a sufficient magnetic field. Regulating dwell time is critical for achieving the correct energy transfer to the ignition coil and, subsequently, to the spark plugs.

4. Generating High-Voltage Spark:

   • When the points open, the sudden interruption of current induces a high-voltage spark in the ignition coil's secondary winding. This high-voltage spark is then sent to the spark plugs, igniting the air-fuel mixture in the engine cylinder.

5. Maintenance of Ignition Timing:

   • The opening and closing of the contact points help maintain the ignition timing within the manufacturer's specified parameters. Accurate ignition timing is essential for efficient combustion, fuel economy, and overall engine performance.

6. Wear and Replacement:

   • Contact points undergo wear over time due to the repeated opening and closing action. Regular maintenance involves checking and adjusting the points or, in some cases, replacing them to ensure consistent ignition timing.

7. Linkage with Distributor:

   • In traditional ignition systems with a distributor, the contact points are often part of the distributor assembly. The distributor rotor, driven by the engine's camshaft, is positioned to open and close the points at the correct time for each cylinder in the firing order.

It's important to note that modern vehicles commonly use electronic ignition systems, which have largely replaced traditional contact points with solid-state electronic components. Electronic ignition systems offer more precise control over ignition timing, increased reliability, and reduced maintenance requirements compared to contact point systems. However, contact points are still found in some older vehicles and classic cars that retain their original ignition systems.