cam aggressiveness question

What determines how choppy a cam sounds at idle? Is it lobe seperation? From what I've looked at sleeper cams are higher, around 116 and 117, and normal cams vary from 108-112

Or does that not have much to do with it? Also, how does lobe seperation effect power?

The best way to explain it is that the more of the exhaust stroke the intake is open the "choppier" the exhaust will sound. In terms of specs, more overlap is what typically leads to this. You create more overlap with a narrower LSA and/or more duration. Take a look at Comps "Thumpr" line, designed to sound "radical" while not really being radical. They have relatively short intake duration but a long exhaust duration and a slightly tighter than normal LSA. The original series are HR SBC cams and they have 14 degrees more duration in the exhaust than the intake and 107 degree LSA. BTW - IMHO it is silly to pick a cam by sound, power is what I am after. But if that's what you like, go for it.

Rich

You need to look at the overlap numbers. Overlap is affected by duration and LSA. However, numbers are not everything. Lobe shapes can affect overlap as well.

You need to look at the overlap numbers. Overlap is affected by duration and LSA. However, numbers are not everything. Lobe shapes can affect overlap as well.

Good point, and the reason why many people look at overlap at 0.050" lift rather than using advertised duration.

Rich