[Formulajones]

All the years I been doing it, they are never exactly right out of the box.

It's not just the cam, nevermind the cam specs possibly being off, you also degree for other reasons. All the key ways on the crank, on the cam sprocket, on the crank sprocket, on the cam itself all are built with a tolerance that isn't exact and all those tolerances stack up.

All it takes is a keyway to be off a degree here, a degree there, and next thing you know you think you've lined up your dots not knowing the cam is off 2-3 or 5 degrees in one direction or the other.
Will it run ok? Sure. But not optimum.
I've seen them off as much as 6-7 degrees and I remember an engine builder telling me he's seen even more.

So it's always best to check to make sure the basics are set. Then if you want to get fancy and check intake to exhaust lobe relationship on overlap and move things around to really dial things in.