What does the timing belt do?

[noob-e]

I searched and did not find my answer. I understand that the timing belt hooks around the cam gears, which in turn rotate the can shafts and so on....but

What is the big deal with "timing"? The timing belt is basically a big belt with a bunch of equally spaced "teeth", right? If you have to change the timing belt, can't you just pop it off and throw on a new one? How can your timing be off? How do you adjust timing? Why is it such a big (expensive) deal to replace the belt?

Thanks in advance

 

[DSMNightmare]

I searched and did not find my answer. I understand that the timing belt hooks around the cam gears, which in turn rotate the can shafts and so on....but

What is the big deal with "timing"? The timing belt is basically a big belt with a bunch of equally spaced "teeth", right? If you have to change the timing belt, can't you just pop it off and throw on a new one? How can your timing be off? How do you adjust timing? Why is it such a big (expensive) deal to replace the belt?

Thanks in advance

OK here is a simplified way of putting it. The timing belt controls the valve timing to ensure that the valves open and close in conjunction with the pistons, and ignition timing. No you can't just pop off the belt because you have to replace the tensioner and water pump at the same time. This means that odds are something is going to move. In a perfect world where you could ensure that none of the gears would move from thier timing marks I guess you could do this. Look at www.vfaq.com and see the steps involved in doing the timing belt for your car. It is very involved and you are working in very closed quarters. Also timing can be off on a timing belt when the belt streaches with age or wear. This can create slack that the tensioner can't necessarily make up for. Then what happens is a belt can "jump" timing and be off. sometimes just one tooth sometimes so bad that the valves get bent.

To adjust valve timing on a 1G DSM you can use the CAS (cam angle sensor) but 2G CASs do not have this option I don't think. Also you can do it with cam gears. This is probably one of those tuning things that you should not even try until you get a lot of tuning experience under your belt.

 

[noob-e]

Thanks, that helped me understand.