AO Platinum Member
Join Date: Feb 2002
Location: The land that Time forgot
No no no... that is not quite right.
The Golden Lodge plugs have no outer electrode but 4 skinny metal tabs instead. That is a way to make sure the spark always has an alternative "path of least resistance".
Having one electrode or many makes no odds to the sparking. There is always only ever one spark at any one time - it occurs at whatever electrode-to-centre path offers the least resistance to the spark.
A single electrode plug has no option except to always use the same path, hence the multi-electrode plug offers a miniscule advantage. If one electrode becomes worn or dirty, another one that offers less resistance is used instead. The plugs also tend to last longer as each electrode is in theory only used 1/4 as much.
A platinum electrode will last longer as it harder in the first place and resists the build up of carbon and fouling. As that stuff burns off, it heats the electrodes and burns them up.
The projecting nose electrodes (the "P" in a NGK designation e.g. BPR8EGV ) is designed to place the spark at the optimum place for the car it is intended for. Cars with high piston crowns don't need a projecting nose plug and indeed, putting one in there is likely to let the plug bash the top of the piston.
The heat rating of the plug is dependent on the construction and how well it takes heat away from the electrode. A projector nose plug can be colder than a non-projector and vice-versa.
You absolutely can't guess the heat rating of a plug just by looking at it, though a multi-electrode, platinum tipped jobbie would be rather more plug than you need in a 1.0 litre shopping car.
No bullets for Chaingun..