RE: About O.S #8 plugs!
the #8 OS plug is not really suited to rich running. For 90% of modellers the #6 or #7 plug is much better.I find the #8 works well in hot engines running at high specific output. These would be the engines that are refered to as bored out e.g., the 55AX which is a bored out 46, or the 75AX which is a bored out 60. Under stressed engines work better with hotter plugs