It is not as simple as it seems. It depends on the spark plug, the intensity of the coil and the compression of the engine. Larger gaps produce more power but require more coil for a hotter spark. Higher compression requires more spark power (coil) and high RPM engines usually use less gap. However since the Atomic 4 is around 9.3 compression, and best power RMM is around 2400, the gap can be quite large if the coil is reasonable. In auto racing we use a very large coil, relatively small gaps and really good plugs that rarely foul. Using the same heat range plug with platinum tips and thin wires we have very little fouling. I am sure the Atomic 4 would do well with this type of plug.