Record that number in degrees for further calculations.Look at your inner dial on the dial indicator and record that number to help achieve our next step, however some dial indicators do not have this feature and is not needed to proceed. Proceed to rotate the engine until your inner dial is back on the number it left from.Go back to the degree wheel and write down the degrees it now reads.Add these two readings together and divide the answer by two.Look at the degree wheel and write down the number of degrees shown by the pointer.Turn the engine by hand in the opposite direction until the piston comes up and stops on the piston stop again.
Example:-10° Opening After Top Dead Center (ATDC) 39° Closing After Bottom Dead Center (ABDC) 180° Distance from Top Dead Center (TDC) to Bottom Dead Center (BDC)=209° Total Duration @ .050 inches of lift209°/2 = 104.5°104.5° 10° = 114.5° Lobe Center If you have adjustable gears move them at this time and redo above procedure.
If there were no manufacturing tolerances, you would only need to line up the marks on the timing chain sprockets and the cam would be degreed, but with a group of components (the camshaft, crankshaft, timing chain, and sprockets) all with their own standards and tolerances that when installed, can stack up against you.
You can never be sure that the cam is in its correct position until you degree it in.
Now either move your pointer by this many degrees, or carefully loosen the degree wheel (without disturbing the position of the crankshaft) and move the wheel this required amount.
Retighten the bolts, and rotate the engine again making sure that the readings on each side of TDC are equal degrees away from zero.