The principle is you have to align TDC ( Top Dead Center) the camshaft,
the crankshaft and piston # 1 position at top when both intake valves
and exhaust valve are close.
If you follow these following steps, it is a piece of cake.
1- Take off the valve cover to expose the camshaft.
2- Take off all spark plugs
, so you can be able to turn the camshaft without any resistance.
3- Turn the cam shaft until the mark on the camshaft pulley aligned with the 0 calibration mark.
4- Put a screwdriver to into the cylinder # 1 to make sure it is at the top. Then remove it.
the camshaft and at the same time notice the intake and exhaust valves
for cylinder # 1 are both closed and the notch on the camshaft is
aligned straight with the crankshaft mark.
6- For a sanity check, from the spark plug
wire # 1, trace back to the distributor cap. Carefully take off the cap
and see the rotor is in the position contact to the plug wire # 1. Then
put the cap back as it was.
This is to ensure you have spark at the combustion stage when all valves are close and piston is at the top.
With everything is as said, now you put in the timing belt at no
turning any position of the crankshaft or the camshaft. If the belt
teeth is not aligned correctly, you have to take it out and put it back
to provide the mark from crankshaft and camshaft are perfectly aligned.
8- Make sure you loosen up the timing belt tension to put it in easily and tighten it up after have correct tension.
9- Put everything back then you are good to go.
10- Don't forget to replace the Valve cover head gasket to prevent the oil leak.
Good luck and have fun in your hands-on action