Ok, this is not the most common subject but surprisingly enough, not many fully understand what the differences are in spark plug heat ranges.. This is going to be a down and dirty quicky explaination... (some liberty taken on some specifics)
how hot a spark plug is has nothing to do with the "spark" part of the plug..
When changing heat ranges, you are changing the "thermal" aspect of the plugs operating parameters.. IE the plug is "physically" hotter and not a brighter or hotter spark. (seems to be where some confusion lies)
The issue with "too hot" a plug goes right to basics..
If the plug is too hot, it turns into a "glow plug" for lack of better term. The engine A/F mixture will ignite off this "glowing" plug just it can off glowing carbon.. In short "pre-ignition" ouch... Too cold? the plug will carbon up and "foul" (better of the two options, read into that what you want)
Anyway, this heat change is achieved by changing the base electrode dimension..
Longer taller center electrodes make the plug run physically hotter as it is unable to pass as much heat from the plug to the cylinder head. (some also modify the negative electrode too) A gasket or taper fit plug work differently too as does a spark plug not properly torqued. A loose spark plug can overheat and cause damage..
A short stubby fatter center electrode can push more heat down the plug to the body in a shorter amount of time thus making the plug run "cooler"
Reading a "plugs heat range" requires you look at the porcelain insulator and seeing where the color change happens.. (takes a few plugs to understand what you are looking at)
how hot a spark plug is has nothing to do with the "spark" part of the plug..
When changing heat ranges, you are changing the "thermal" aspect of the plugs operating parameters.. IE the plug is "physically" hotter and not a brighter or hotter spark. (seems to be where some confusion lies)
The issue with "too hot" a plug goes right to basics..
If the plug is too hot, it turns into a "glow plug" for lack of better term. The engine A/F mixture will ignite off this "glowing" plug just it can off glowing carbon.. In short "pre-ignition" ouch... Too cold? the plug will carbon up and "foul" (better of the two options, read into that what you want)
Anyway, this heat change is achieved by changing the base electrode dimension..
Longer taller center electrodes make the plug run physically hotter as it is unable to pass as much heat from the plug to the cylinder head. (some also modify the negative electrode too) A gasket or taper fit plug work differently too as does a spark plug not properly torqued. A loose spark plug can overheat and cause damage..
A short stubby fatter center electrode can push more heat down the plug to the body in a shorter amount of time thus making the plug run "cooler"
Reading a "plugs heat range" requires you look at the porcelain insulator and seeing where the color change happens.. (takes a few plugs to understand what you are looking at)
