What is the reason for degreeing a cam? watched them do it on tv and
the info they got is the same that comes with the papers on the cam. all they sad was the centerline was such and such. so i'm asking, what's the purpose? thanks

 

Purpose? With modern off the shelf camshafts, very little. If you buy a custom grind, you degree it to make sure it's exactly what the cam card says.

All I degree a camshaft for is to make sure the ignition timing mark is exact when the piston is at TDC. This requires using a piston stop with a degree wheel. I don't change the cam timing but I have an adjustable timing pointer and will adjust it to make sure the ignition timing is exact.

 

Degreeing the cam assures you that the cam is in the place where it was designed to be...there are many variables that can affect the position of the cam, the holes for the cam gear, the alignment dowel postion, in both the gear and cam, the spot where the cam gear and crank gear are marked, chain stretch etc.. add up a few differences and you can end up 3-4 degrees off.
a second reason to degree aside from finding EXACT top dead center is to know the exact starting point of where the cam is phased so when you retard or advance the cam to tailor your RPM band you know where you started. Retarding the cam will move your whole power band up and advancing it "moves" the power band lower in the RPM range. Piston to valve clearances increase and decrease when the cam is moved in relation to the crankshaft. retarding and advancing the cam can also change the PSI the cylinder makes on a compression stroke, more or less detonation sensitive...not by alot but some. Most street guys advance the cam to gain low end torque and increase cylinder pressure which helps with low speed operation with larger duration cams, depending on a choice of cam for the drag racer they may retard thiers more to increase the top end response and rpm range.

 

http://www.carcraft.com/howto/116_07...aft/index.html

 

You should always degree a cam before installing it.
That way you know that it is correct and not have to worry about it later if you encounter problems. (not built on Mon. or Fri.)

I have seen cams off as much as 4 degrees.
It all depends on where the pin was indexed when ground, operaters can make mistakes.

 

I know Don knows his stuff but I want to make it clear that he means the cam should be degreed before FINISHING the installation. There is no way to degree a cam without installing the cam in the block first.