These rockers GO through the Exclusive KillerCrate Rating process
Not all Rockers are created equal. GM Spec is 1.5:1 and after measuring hundreds, we found that some are just 1.45:1.
A rocker arm in your 602 engine takes a rotating cam lobe and turns it into an up and down motion that opens and closes the valves.
Here's how it works. As the cam comes around, the cam lobe pushes the lifter and pushrod up, which lifts the back side of the rocker arm. When the backside lifts, the other end of the rocker rotates to push down on the valve stem; compressing the spring. As the cam lobe rotates away, the rocker arm rotates back and the spring pressure closes the valve.
Rocker Arm Ratio determines how much power it can transfer to the valve stem. In a GM Crate, the GM Spec rocker arm ratio should be 1.5 to 1. Meaning that the rocker should move the valve 1.5 times the height of the cam lobe which is 0.435 for intake and 0.460 for exhaust. Since the intake is smaller to start with, the lift is critical.
If you have a crummy rocker arm - your Valve will open significantly less than it should. Less "Valve opening" on an intake valve means less power. Therefore you want your best rockers on your intake valves.
We use a Special Rocker Rating Machine we created to measure all your rockers. Rockers are rated as Green, Yellow or Red.
Green are the best and go on Intake Valves. Yellow are rated for Exhaust Valves and Red are really not good enough to use.
The Packaging you will receive are marked as Intake and Exhaust.