He Linux
I found a VERY VERY nice source of info about Spark technology:
http://www.stealth316.com/2-sparkplugtech.htm
It says that extended spark plugs will accumulate carbon deposits faster.
And something interesting:
Factors Affecting Plug Temperature
The operational factors that affect spark plug temperature include the following.
Ignition timing advance - temperature increases as advance increases; 10 of advance can cause 70 to 100C (128 to 180F) of temperature increase; note that pre-ignition temperatures also elevate with more advance.
Compression pressure - temperature increases in direct proportion to cylinder pressure or as compression ratio or boost pressure increase; note that pre-ignition temperatures decrease as cylinder pressure increases.
Engine speed and load - temperature increases as engine speed or load increase because these change the cylinder pressure (or the intake charge density); with the highest temperatures occurring during wide open throttle (WOT) conditions.
Air-fuel ratio - temperature is at a maximum around 13:1 A/F; very rich mixtures can cause fouling.
Tightening torque - temperature increases slightly if the plug is loose, and decreases very slightly if the plug is too tight; proper torque for our spark plugs (14-mm flat seat with gasket in an aluminum head) is 18 to 21.6 lb-ft (24.4 to 29 Nm).
