Rules of thumb to live by

[myRC]

* Use a hot plug with low nitro (less than 24%), and a cold plug with high nitro (more than 25%).
* If you remove the glow starter from you idling engine, and notice an immediate drop in RPM, you may need a hotter plug or more nitro.
* If your engine has a tendency to backfire a lot, you may be using a glow plug that's too hot, or you may need fuel with less nitro.
* Most hot plugs can take up to 2.0 volts starting power without burning up, while most cold plugs prefer 1.2 to 1.5 volts starting power.