Spark plug gap

In my continuing saga to smoot

In my continuing saga to smooth a rough idle I had the spark plugs pulled from the stb engine. The plugs apparently were never gaped when installed two years ago the gaps ranged from .012 to .020. They are supposed to be .045. New properly gaped plugs result in a much quieter? smoother engine.
What are the consequences of plugs with too small of a gap and can any permanent damage result? Why would the engine be quieter?

"The engine is quieter because

"The engine is quieter because the spark plugs are doing their jobs correctly, this lets all cylinders work as a team. The 'noiser' state is when some are woking and some aren't - that "lack of cooperation" was audibly noticeable.

The 0.020" gaps were probably ok but the 0.012" gaps were suboptimal. based on my limited understanding, there are a few understood consequences. The spark starts 'earlier' than designed. Voltage required is a function of distance. Voltage build up takes time, even if measured in microseconds. The end result is the spark occurs at lower than designed value so not a much energy is tranfered...bottom line consistent but poor ignition (weak spark). This weaker spark can also lead to "quenching" (another form of weak spark). Another is small flame kernel - think of it a match where you should be using a torch.

The biggest damage I'm aware of is that done to your wallet from reduced efficiently (more fuel burnt). I would surmise that you could cause some engine damage if operated like this for a sustained period of time but that's unlikely."