I have a Comp 280 cam that was in a 396. It has .516 lift I believe... can't remember lobe separation angle. But anyway, it had a slightly rough idle in the 396 that was .030 over. I just pulled a cam out of a .060 over 454, which had a smooth idle and I had assumed it had a stock or RV cam in it. However, visually, they look identical. I know that the only way to tell for sure is to mic it. But if they are the same cam, is it just the difference in cubic inches that makes it sound milder in a 468 vs. a 402?