HI....on our 57/ 235 engine we have a Langdon HEI dizzy. Spark Plugs....what does the gap of a plug have to do with engine performance? At low speeds is a bigger gap recommended and if you are racing around is a smaller gap needed. I always thought that the gap is set and the plug you buy get is either hotter or colder? OK...I need some GAP help....set me straight. T/C Steve