what are the differences between the colder degree spark plugs? for what reason do you need a colder plug?

 

Well what heat ranges for a spark plug means is it's ability to remove heat from the combustion chamber. It's determined by: the length of the center insulator, the ability of the nose to absorb and transfer heat, and the material of the insulator and electrode. A colder spark plug will have a shorter insulator nose. It's important because if you are knocking from too much heat in your combustion chamber it'll help remove it more efficiently. BUT the temp in the tip has to remain between 450*C-850*. In other words, if you don't need them don't use them