Finding the right spark plug for your 340 or 440 HP ..

Thanks Guys heat range tho on those is about 5 or 6 .. ok for warm dry weather .. But truth is they no longer make the correct plugs ur using 318 2 bb plugs and 440 RV plugs
big difference .. on heat range . Thanks PS not all of us Have $$$ for crappy MSD system
which had almost last as long as those plugs .. less than a year ..