hey guys, if anyone knows a website or thread that explains what glow plugs to use for which engines under which circumstances, it would be nice. it would just be nice to have some sort of guideline to go by.

I may get some arguement here, but I tend to keep it simple for glow plugs. 2 stroke engines get the OS #8 or OS A3 plug, I use the A3 for all of my engines but others like the #8 so I mention it here. Different climates might get better performance with the #8, and it works for then use it instead of the A3. For 4 strokes I use the OS F plug. And that's all that I use. I have no glow plug problems using these plugs.

Ken

In general sport flying, the hotter the fuel and higher the compression, the colder the plug. Lower compressions and colder fuel need hotter plugs. For a Super Tigre, hot fuel is anything over about 12% Nitro fuel. For a Dub Jet, it might be close to 20%. ABC engines are usually higher compression engines. Generally one just has to work it out. Regardless of the popular hype, I still prefer Idle-Bar plugs for sport and scale. Sport and Scale, I like the McCoy 50 and 59. For racing a McCoy 9 generally fits the bill. In summer 5% nitro with a good M-50 IB or a non-IB M-59 works just fine for most engines.

edited to change a verb.

http://www.osengines.com/accys/choosing-glowplugs.html
http://www.osengines.com/accys/glowplugs.html

thanx alot for those links bruce, thats what i was after. RCKEN i use those A3 glow plugs too and i'm having little probelms, was just wondering if maybe i should be using something different or if i should be changing them depending on the temp or conditions. thanx again guys.

so does the hotter plug just cause the fuel to ignite quiker or how does that work.

Pretty much

so it would give me more power but heat up my engine to much or what?

I use a couple different plugs because I run 15% nitro in my plane engines and 50% and higher in my boat engines. When you run higher nitro, or higher compression, the fuel will ignite at a lower temperature. If the fuel ignites too early, you get pre-ignition, the same thing as pinging in an auto engine. Pre-ignition is bad for a couple reasons. First, it creates extra heat. Second, it actually damages the engine. When you look at the top of the piston in an engine that's been run with pre-ignition, you can actually see pitting. In order to counter pre-ignition, you need to reduce the temperature so the engine fires a bit later. You can do this in a variety of ways including running it richer, which uses more fuel, lowering the compression ratio, by shimming the head higher, running lower nitro fuel, or by running a cooler glow plug.

For most sport airplane engines running a reasonable amount of nitro (15% or lower) and not run too lean, you can run a standard medium to hot plug such as OS A3, 8, McCoy MC-59, and several others. If you're running higher performance applications where you've increased the compression ratio or are running higher nitro, a colder plug, such as the McCoy MC-9 or others would be in order.

For reference, I use the following plugs:
Low nitro: OS 8, McCoy MC-59, and OS F for my 4 stroke engines
High nitro: McCoy MC-9 and K&B 1L

I have found that athe Fox Miracle plug serves me very well in both my 4 strokes and 2 stroke engines, all with 10% nitro fuel. Unless you have a cross scavaged engine, the idle bar does not buy you any advantage, may actually be a detriment.

I use an OS#3 in all my 2 stroke engines and i use Omega 10% fuel, and all engines have ran great with this plug from the heat of summer to the cold of winter. The engine i have are:

TT PRO .46
TT PRO .36
TT GP .07
Magnum .15XL
Magnum .15XLS
Magnum .46XLS
OS .40 LA

#3?? They make an A3 plug but no #3 plug.

Sorry A3