its the sprocket that goes on the front of the cam, but it is adjustable unlike the standard one. i think its so you can adjust your cam

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its the sprocket that goes on the front of the cam, but it is adjustable unlike the standard one. i think its so you can adjust your cam[/quote]


ok thanks so will i have to cut a hole into the head inorder to fit the sprocket to make it work??

The Vernier cam sprocket is so you can adjust the cam timing to where it needs to be OR where want it to be....ie: the cam has an advanced grind...meaning when it was ground, it wasn't quite in the centre spot, so it will need to adjusted to get it right.
I have a billet cam that has 1* adv grind.......they can be the other way too, retarded.
Now, when you want to have different timing, usually advance it, by 2* or 4* this gives you more torque off the line.......changing when the torque comes on.

Its a replacement for your original, and no you dont need to cut a hole in the head/rocker lol. When you install it you adjust it to what you want, and to re-adjust you only need to remove the rocker cover, and intake off the BBM, if you have one. Its only a couple of bolts, no big drama.
Like CJH said, advancing generally brings the torque curve lower in the rev range, and for a street car this is what you want. You will lose top end, though IMHO, for a streeter, the extra usable torque down low is well worth it.

Yer. Thx for all the help