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Timing Chain/Cam Gear Timing Marks/Harmonic Balancer
People often get confused where the timing mark on the cam gear aligns with the crank gear. Notice on the diagram the position of the mark on the cam gear in relation to the crank gear; with the crank gear mark at the 12:00 o'clock position the cam gear mark should be at the 12:00 o'clock, you will be timing the engine off the #1 spark plug at top dead center (TDC). With the crank gear mark at the 12:00 o'clock position the cam gear mark should be at the 6:00 o'clock, you will be timing the engine off the #6 spark plug at TDC.
Note the crank gear keyway is at the approximate 100 o'clock position when the crank gear is properly aligned.
If you are breaking down your engine to replace the timing chain and/or camshaft be sure to set the timing marks as shown (typically with the cam gear mark at the 12:00 0'clock position) before removing the old chain to make installation less of a hassle.
If you are breaking down your engine beyond just the timing chain and/or camshaft it really doesn't make much difference where the timing marks are as you'll need to set them again later on.
Harmonic Balancer
The harmonic balancer, also known as a tortional dampner, is fitted to the crankshaft to counter tortional and resonance vibrations from the crankshaft on an externally balanced engine. Typically, a non-high performance engine the balancer has a small groove to align with a timing tab to indicated top dead center. The timing tab can be physically attached to the timing cover or may be a bolt-on tab and it will have several marks to show advanced or retarted timing. See Basic Timing for more.
High-performance aftermarket balancers have advance timing marks on
the balancer itself.
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