i crossed refrence the spark plugs i pull out of my stock 454... plugs i pulled out are champion rv8c. went to autzone and they had autolite and ac delco available when they cross refrenced the champion. the autolite was on my list so i went with the autolite. well the reach is the same on the plug from taper, but i fear that the new plugs i got ( autolite 145 ) are hotter than the champions??? here are some pics maybe one of you with spark plug knowledge can help me out ? comparing both ceramic insulators, they seem to be the same. the champion plug i cannot see all the way down the plug. I think the autolite is hotter because the thickness of the thread wall of the plug is alot alot thinner then the champion. champion thread wall thick ness alot thicker, and the gap between the thread wall to insulator is alot narrower? autolite very thin thread wall and gap from thread wall to insulator huge.... im a bit stumped on these plugs lol? also notice the taper body on the plug is alot longer than the champion. what are your thoughts? does the gap between the thread wall to insulator even matter. as you guys can see , im very observent and paranoid 

okay cool, thank you for your help... im assuming the thread thickness doesnt matter. i wasn't sure if that gap and wall thickness had an effect on heat transfer from the insulator to the tapered part of the head. thanks again