Bill,both Denny & camaro fever68 know more than I do but I'll add one more note.LSA doesn't necessarily have such a 'hardfast' rule.But they are both correct.You in fact can have a tight LSA and yet the cam be ground as though it is a wide LSA. I only mention this because if this is someones reasoning in cam selection they better be sure and study all the characteristics of the cam or it won't be what they wanted,there are plenty of 'odd' ground cams on the market.