ORIGINAL: Bax

There are a lot of myths and misinformation about glowplugs.

First off, they DO keep working after the ignitor's been removed. The platinum element gets hot when exposed to methanol. It also catalyzes the combustion process. Yes, a certain amount of compression is needed to allow the fuel/air mixture to fire, but you also need the catalysis of the platinum element of the glow plug. This catalysis happens when the temperature of the plug and the compression in the engine reach a certain point. You use the battery to heat the plug to get it started. Further combustion then keeps the plug hot. If the engine needed a plug to keep going, then it wouldn't quit when the plug's element gets beat up. There are cases where the plug will glow when you apply the battery, but the engine won't run. That's because the element's become contaminated, and it can't catalyze the engine's firing.

The heat range of the plug is used to contol detonation. "Hot" fuels (high nitro) need "Cold" plugs, and vice-versa. If you're engine's detonating, and you can't control it with compression or mixture, then you need to go to a colder plug.

Plugs such as the O.S. Max #8 and #A3 are general-purpose plugs that work in most two-stroke engines running on fuels with nitro content up to 15%-20%. Above that, then go to the colder plug.