What is spark advance mechanism?

The distributor’s centrifugal timing advance mechanism makes the spark occur sooner as engine speed increases. Many of these engines will also use a vacuum advance that advances timing during light loads and deceleration, independent of the centrifugal advance.

What is spark advance in IC engine?

Spark advance is the time before top dead center (TDC) when the spark is initiated. It is usually expressed in number of degrees of crankshaft rotation relative to TDC.

Why spark advance is required?

Advancing the timing means the plug fires earlier in the compression stroke (farther from TDC). Advance is required because the air/fuel mixture does not burn instantly. It takes time for the flame to ignite the all the mixture. However, if the timing is advanced too far, it will cause an Engine Knock.

Which spark advance mechanism works on the speed of the engine?

Explanation: Actually, the vacuum advance mechanism operates independent of the centrifugal advance mechanism. 6. The larger throttle opening means the possibility of better mixing and combustion during idling. The centrifugal spark advance is essential to compensate for the increase in speed of the engine.

What is an advance mechanism?

Definition & Description. The mechanical (or centrifugal) advance is an Ignition Timing control mechanism built into most distributors. It is made up of: An advance plate or cam attached to the trigger mechanism inside the distributor, and. Springs that control how fast the weights are flung outward.

What should my spark advance be?

What should my spark advance be? Your spark advance should always be at 15-35 degrees before TDC or the top dead center of the power stroke which is mostly dependent on the speed of the engine.

What is a good spark advance?

That is typically 15-35 degrees before TDC (top dead center) of the power stroke depending on the engine speed. Best power is achieved when ignition timing is set to fire the spark ahead of time to reach that peak pressure at about 2 degrees after TDC.

What is ignition advance?

Ignition advance is the condition when ignition of fuel occurs earlier than the correct ignition timing. Ignition of mixture takes place near the end of compression stroke. Spark advance may also cause the fuel to explode suddenly under certain operating conditions.

Why is mechanical advance necessary?

As an engine revs up, we need to allow even more of a head start for the spark plug in order for complete combustion to occur. For this reason, a mechanical advance is built into most distributors.

What is the difference between vacuum advance and mechanical advance?

Definitions. Mechanical advance uses the weights and springs in the distributor to rotate and alter the timing sensor shaft’s position relative to the engine’s position. Vacuum advance timing uses a manifold vacuum that reacts to the rotation of a position sensor mounting plate located in the distributor.