I have a set of heads i just put on my sbc they are cast 194's. I think they are from a corvette. I went to buy sparkplugs for it and they asked me if they were tapered or not I have no idea. How can i tell which plugs i need? Looking at the spark plug hole it's hard for me to tell what im looking at without a comparison. If someone could send a pic of both types or has a good explanation that would be cool the guys at napa are only so helpfull.