[Chevy454]

Sorry about that, Marlin! Jim's right on the money with the acronyms:

LSA - Lobe Seperation Angle
LCA - Lobe Centerline Angle

The LSA is the amount of serperation, or overlap, between the intake and exhaust lobe. The "wider" (larger) the number, the less overlap, and the more fuel/air that is trapped in the cylinders at low/mid engine speed, and vice versa. This is ground into the cam, and thus, can't be changed. This also has a great effect on idle, and anything under 112 will generally have a pretty good lope to it (that's why I questioned the 106 LSA of the Comp unit). I believe the LSA of the 143 cam is 114, and I think the original LT-1 cam is the same (114). The LSA is independant of the LCA.

LCA is the centerline of the intake lobe, and like Jim said above, tells you how much your cam is advanced/retarded. This is changed by degreeing your cam to whenever you want it to come in. I believe most of the older/original cams were ground advanced (the 143 cam was ground with 6 degrees advance!), which is fine on the stickies, but is hard to handle if you are running on the skinnies!