Will i gain any advantage by fitting this type of plug in my 1949 Rover P3/75 sedan, would they burn a bit hotter and eliminate this soot deposit that i am encountering at the moment. i have NGK BP5ES in the vehicle now and the car runs ok but they soot up rather quickly . so i regularly remove and clean, put them back in and away we go for a while. i have checked the mixture and the timing and all seems to be ok. any advise would be greatly appreciated. best degards Derrick.Smith.