Plug readers: What would you do??

Dale Davies said

You must be an unleaded fuel newbie. Unleaded plugs show a greyish tinge, while leaded fuels left a tan color.

Click to expand...

Not true. Colour is mainly dependent on temperature reached at time of ignition and mixture quality and AFR of gas species. ANY time you have an AFR at the plug Richer than stoic Carbon HAS to be left over after the burn proceeds. This carbon is what coats the plugs and indicates what the AFR is at that time. The first stage of the burn is hydrogen the second is carbon. That greyish tinge is most likely exhaust residual left behind due to poor scavenging or too much overlap.

Its not the AFR of what you give the cylinder but the AFR of the "GAS" at the plug at time of ignition. You can give a cylinder a 12.5 to 1 AFR and still get a white plug because the "GAS" around the plug is still lean as a ration compared to the rest of the cylinder because you haven't converted the liquid fuel to a gas to burn in the first place.