The top line of the timing mark is the TDC marks. The marks are for both cylinders 1 & 6 for the cam shafts. The mark on the bottom of the timing cover below cylinder number one piston is used to find " Top Dead Center" when checking spark plug timing or camshaft timing.. To see it on the crank shaft hub pulley (or harmonic balancer) you will need a timing light. Timing marks are shown below.
