What Happens When the Spark Plug Gap Is Too Big?

Spark Plug

Too small a spark plug gap is bad for the engine. The ignition will not be smooth and the fuel mixture might not burn completely. But what about too big a spark plug gap.

What happens when the spark plug gap is too big? Although a larger spark plug gap will have more contact with the fuel mixture for ignition, it draws too much voltage to generate a spark and is an inefficient way of spark ignition in the engine.

The same applies when the spark plug gap is too small as well. Too small a gap means not enough contact with the fuel mixture. As a result, there might not be proper ignition of the fuel mixture in the engine.

That’s why it is always desired to have the spark plug gap in the optimum range. Neither too big nor too small a gap.

Let’s dig in for more details.

Is a bigger spark plug gap better?

A bigger spark plug gap is NOT at all better for the engine.

The spark plug gap is the gap between the center electrode and the side (ground) electrode in the spark plug. This gap is essential since this is where the spark is generated. The electric arc flows from the center electrode to the ground electrode through this gap.

Now, when the spark plug gap is too big, the distance between the center electrode and the ground electrode is higher. The electric arc will have to travel a longer distance than necessary.

This has its advantage. The spark will have longer contact with the air-fuel mixture in the engine. As a result, there will be a proper ignition of the fuel mixture paving way for the combustion process.

However, this large gap is still inefficient for spark plug ignition. The electric arc has to travel a longer distance and will hence, draw too much voltage. The increased contact with the fuel mixture provides no added benefit since an adequate contact is sufficient for proper ignition.

In short, too big a spark plug gap is not required since it draws too much voltage and is an inefficient way of spark ignition.

Does the spark plug gap affect timing?

The spark plug gap will NOT affect the ignition timing. Nor will it affect the combustion timing in the engine.

However, the spark plug gap can affect the ignition itself if it does not spark ignite the fuel mixture in the engine.

This can happen when the spark plug gap is too small. The small gap will mean less contact of the electric arc with the air-fuel mixture in the engine. As a result, the spark will be too small and the limited contact with the fuel mixture might end up with no ignition at all.

So, too small a spark plug gap is not good at all. While it won’t affect the timing, the limited contact might affect the combustion process with no burning of the fuel in the engine.

In short, the spark plug gap will not affect the timing but might affect the ignition itself if the gap is too small.

Does the spark plug gap affect performance?

An optimum spark plug gap is essential for good engine performance. So, yes, the spark plug gap does affect the engine performance.

In continuation from the previous section, say, the spark plug gap is too small. The electric spark might not come in contact with the air-fuel mixture properly and hence, might not ignite the entire air-fuel mixture for complete combustion. This incomplete combustion of the fuel mixture will lead to less power generation and low engine performance.

On the other hand, if the spark plug gap is too big, the spark draws a higher voltage. If there isn’t sufficient voltage to draw from, then there will be a weaker spark for the ignition. Again, the weak spark will not ignite the fuel mixture properly. Leading to low engine performance.

In short, the spark plug gap does affect the engine performance. We need the spark plug gap to be in the recommended range.

Does spark plug gap affect horsepower?

We are beating the dead horse here.

The spark plug gap does affect the engine performance and the horsepower.

As discussed in the last section, an optimum spark plug gap is essential for good engine performance. If the spark plug gap is too small or too big, the engine will not generate high power and will have low performance.

So, yes, the spark plug gap affects the horsepower generated in the engine. If the spark plug gap is in the recommended range, the horsepower generated will be higher. If, on the other hand, the spark plug gap is too small or too big, the engine will generate far lower horsepower.

What does increasing the spark plug gap do?

Increasing the spark plug gap will first and foremost increases the distance for the spark generated (duh!). The electric arc will travel from the central electrode to the ground electrode.

The increased gap will result in a longer electric arc. This leads to a higher contact with the air-fuel mixture, which in turn, leads to better ignition of the fuel.

However, if you increase the spark plug gap too much, the center electrode will draw too much voltage since the electric spark has to travel a larger distance. This is an inefficient spark ignition way. in case the electrode is not able to draw sufficient voltage, the spark will be weaker and might not ignite the fuel mixture properly.

So, increasing the spark plug gap from too small a gap to the recommended range is good. This will increase the contact with the fuel mixture and improves fuel combustion.

But too much gap increase leading to a large spark plug gap will have diminishing returns. The spark ignition process will draw too much voltage, is inefficient, and if the electrode can’t draw sufficient voltage, the spark will get weak and might not ignite the fuel mixture completely.