Hi frank
Below is a little about Glow Plugs, I carry many brands and the Merlin plugs mentioned earlier also have a hot plug in their line, as well as the McCoy #59
"Plugs can also be a major cause of trouble, and poor runs. When you first crank the plane, notice if it goes rich and sags slightly when the battery is removed; if so, the plug is normally too cold. This is critical to getting a proper Stunt run.
Most plugs are designed to provide a colder range than we want in C\L aerobatic engines , and you should try to get the right range for the motor. Many days of testing and much time and expense buying almost every plug on the market has yielded these results ;Thunder Bolt R\C long, T Bolt #3 , T Bolt 4 stroke, Glo Devil RC #300 long, Enya 3 & 4, Fireball RC long, the Hobby Shack RC long, SIC RC long a few of the OS hotter plugs and some of the FOX long and Miracle plugs are best plugs for our use. In almost all instances, use a long plus, as they will be substantially hotter than the shorts, plus they are deeper in the combustion chamber and this tends to keep things hotter and keeps the plug elements cleaner.
A lot of times the plug problems show up as rich inside maneuvers and leaner outsides; this happens because gravity and centrifugal force ,forces the oil-fuel charge down on the element on insides, thus cooling the coil and pulls it away on the outside maneuvers, letting it naturally go leaner. I have seen this problem instantly cured by simply changing plugs. Please do not be afraid to put in a new glo plug , or try different types of plugs ."
Randy