"Degreeing the cam" is the way to check and see if the cam you bought actually was ground correctly and matches the advertised specifications.
It is also a means to determine the timing events of an unknown or stock cam.
The keyways allow you to adjust, or compensate the valve timing in relation to the crank as it suits your purposes. Retarding it generally creates more top-end and advancing creates more bottom-end, or torque.
Some manufacturers, like FORD, started to use cams with 4* retard during the emissions era, so advancing that type of stock cam by that amount can perk it up a bit.
It is also a means to determine the timing events of an unknown or stock cam.
The keyways allow you to adjust, or compensate the valve timing in relation to the crank as it suits your purposes. Retarding it generally creates more top-end and advancing creates more bottom-end, or torque.
Some manufacturers, like FORD, started to use cams with 4* retard during the emissions era, so advancing that type of stock cam by that amount can perk it up a bit.