The conventional wisdom used to be "hot blue spark". That's impossible since radio noise suppression "resistance wire" came out in the mid-1950's. A weak-looking yellow/orange spark is pretty common these days, unless some sort of metallic wire is used. Metallic-core wire, either copper or stainless steel, is used in some racing applications, but the cost of getting that hot blue spark is rapid deterioration of distributor cap and rotor connections and rapid erosion of spark plug electrodes due to the high current flow spark. The radio frequency induction plays havoc with AM radios and TV signals in close proximity to a non-suppressed ignition system, also.
Jerry
