basically in a glow engine there is no timing to adjust like in the old v-8 to eliminate engine knok,back then if you haf engine knock you used premiom gas or retatrded the ignition a feww degrees to eliminate the knock.glow engines have detonation which is about the same thing.it can be controlled by compression,nitro content and plug.usually with the no nitro fuels you use a hot plug and with high nitro fuel a cold plug.in between can be a hot or medium plug.