It was suggested that based on the condition of my plugs, I should run a cooler heat range. The white build up is ash... burning the oil that is in the cylinders (rings?)
For me heat range tuning on plugs is 'fine tuning' after larger variables have been sorted out. If plugs are cooking because the mixture is lean or the timing is late - switching to a cooler plug is hardly the 'next' intervention -
Engine Builder: understanding spark plug heat range. As to 'what' is burning and being deposited on a particular engine's plugs - again this is not about heat range. If cylinders are out of round thereby preventing the oil rings from scraping the walls clean - changing heat range doesn't fix the fact that too much oil is entering the cylinder during the compression/combustion event.
I DO know that after cleaning the deposits off of my plugs, the engine runs as good as it ever has!
Isolating and preventing the source of the deposits is the goal. In a properly setup engine the plugs are 'self cleaning'.
