I understand lift and duration when dealing with cams, but lobe seperation stumps me.

 

http://chevyhiperformance.com/techar...48_0307_basic/

In the "Centerlines" paragraph.

 

One of the reasons it probably confuses you is because it's the ONLY measurement in degrees based on cam rotation and not crank rotation.

For instance.... 260* duration on a cam is 260* of crankshaft rotation.

106* Intake Centerline is measured when the crank has spun 106* past top dead center (aka ATCD).

When looking at a cam from one end (mainly the front), the centerlines of the exhaust and intake lobes are "spaced" a certain number of degrees apart. This is called the Lobe Seperation Angle.

If you were to draw a line from the center of the cam's diameter, then two lines outward to form a "V" using the centerlines of the intake lobe and exhaust lobe of one cylinder, lay a protractor against that point, the amount of degrees that seperates those two lines is the LSA.

IF all else stays the same, the closer together the lobes are (less LSA... 106* instead of 110*), the more overlap there is (the point when both the exhaust valve and intake valve are open at the same time).

Ignore the 3rd grade artistic ability, but maybe this pic will help?

 

Quick and dirty, a wide (bigger number( centerline will give a little more cylinder pressure and better low mid range power. Tighter (lower number) center line will reduce pressures at low rpms but boost high rpm power if you have the compression up to work with the cam.