spark plug indexing

[vintageracer888]

anyone know what it weighs ??

[eb miller]

well my 2 cents of this is a serious hot rodder told me the indexing was noticeable on high compression wedges like 428 cjs' but made no difference to speak of on things like 351c or 429cjs which had staggered valves so i would imagine the effects would diminish still more with a 4 valve head [Non-text portions of this message have been removed]