Step 6: In order to degree cams, you'll need to verify that the centerline of both the intake and the exhaust (intake only if SOHC) are where the cam manufacturer says they should be. Locate the intake lobe you'll be measuring and close its valve lash completely. Make sure that the valve is closed by confirming that the rocker pad is positioned on the cam's base circle, not its lobe. If you're degreeing an engine with variable valve timing like we are, be sure to measure from the appropriate lobe and activate variable valve timing if necessary.
|When degreeing cams, it's important to close the valve lash completely and take all measurements from the top of the retainer, not the rocker arm.|
Step 7: Fabricate some sort of base to securely mount the dial indicator to the cylinder head and place it near the number one cylinder's intake valves. Position the dial indicator's tip on top of one of the number one piston's intake valve retainers. Don't position its tip on the rocker arm otherwise the results will be distorted. In order to reduce geometrical errors, be sure that the dial indicator's needle remains parallel to the valve.
|A fancy cam degreeing setup like this will allow you to verify TDC and check both intake and exhaust centerlines in one shot. A single dial indicator will yield the same results but will take a few minutes longer. (This particular setup also includes a dial indicator for locating TDC.)|
|It's important that the dial indicator's needle remains parallel to the valve. This is the only way to achieve an accurate reading.|
Step 8: Now is a good time to make sure that the dial indicator's needle is set up to display the appropriate amount of travel. If it isn't, be sure to add an extension or adjust it as necessary. In other words: be sure that the dial indicator doesn't max out before the valve has either fully opened or closed. Set the dial indicator so that it reads “0” and rotate the engine until its valve reaches full lift. Verify that the indicator still has additional travel.
Step 9: Rotate the engine back to TDC in its normal operating direction, stop, and set the dial indicator so that it reads “0.” Slowly rotate the crank once again in the same direction. Observe the dial indicator's reading as its respective valve begins to open. Keep rotating the crank in a smooth motion until you've reached exactly 0.050-inch of valve lift as read by the dial indicator. If you overshoot your mark while rotating the crank, continue for another full rotation until you've reached the .050-inch opening point. Record the value on the degree wheel corresponding with the pointer. This will typically occur BTDC.
Step 10: Continue to rotate the engine in the same direction, this time stopping exactly 0.050-inch before the valve closes. Before you can find that value, though, you've first got to locate the point at which the valve fully closes. Think about it: you can't locate 0.050-inch before “X” if you don't know where “X” is. Continue to rotate the crank until the dial indicator reveals that the valve has closed. Be sure to stop as soon as the dial indicator reveals it's closed. If you overshoot your mark while rotating the crank, continue for another full rotation until you've reached the valve's precise initial closing point.