SOHC V6 camshaft timing slots
Use the pointer on the crankshaft position center in conjunction with the markings on the crankshaft damper to determine #1 piston TDC as shown below.
In the above photo the damper has not been pulled in and torqued in position. The red arrow identifies my faded TDC mark. There is a "0" above the TDC line and another line below the TDC line for 10 BTDC. Below the second line is "10" as shown better in the photo below.
Some members remove the #1 spark plug and feel for compression to make sure that #1 piston is at TDC and not on the exhaust stroke. Since the valve covers must be removed to check the timing, I prefer to check the camshaft position sensor "nub" to determine if #1 piston is at TDC on the compression stroke. The photo below identifies the correct position for the "nub".
There is a slot in the end of each camshaft. The slot is off center from the axis of the camshaft. When the camshafts are correctly timed both will have the slot parallel to the head surface that mates with the valve cover as shown in the photo below.
The left camshaft easily stays in the correct position when the camshaft sprocket retaining bolt is loose because the valve spring pressure is minimal. The right camshaft will jump to about 50 degrees before or after the desired position because at the desired position both cylinder #2 valve springs are fully compressed. The special tensioning tool that comes with the tool kit keeps the timing chain taught on the traction side of the chain to preserve the correct timing relationship between the crankshaft and the camshaft. It is especially important when timing the right camshaft due to the spring compression and the left hand thread (tightens counter-clockwise) camshaft sprocket retaining bolt.
A common mistake when timing the camshafts is not having the #1 piston at TDC on the compression stroke when only timing one camshaft. If the camshafts are timed 180 degrees out the engine will run but poorly.
Another common mistake is only using the stock tensioner to tension the chain when timing. The spring pressure of the tensioner is inadequate to assure overcoming the valve spring pressure to rotate the camshaft away from the correct position. The right camshaft is frequently timed incorrectly by the amount of slack in the chain (several degrees).
To check the right camshaft timing it is essential to keep the chain taught on the traction side. This can be achieved with locking pliers afixed to the camshaft between two lobes and applying enough counter-clockwise torque to taught the chain while keeping the crankshaft at TDC.
