cambelt timing marks

[rwillis89]

fitted my cams and new cambelt, lined up the 3 white lines/marks on the belt with the notches on the cam pulleys and the bottom crankshaft pulley, rotated it only to find that after 1 full rotation all the locking pins line up ( 2 in cam pulleys and 1 in flywheel) however the marks on the belt (white lines) no-longer match up with the marks on the pulley. (2 teeth out) then rotated it again and once again all locking pins match but the marks on the belt are now 7 teeth out :S cant get my head round this as i expected the marks on the belt to match up after every rotation...or am i just being daft:S?
help plz!

[TU-Tuning]

Yeah they only line up the first time mate ;) The teeth all change over after the first time. Eventually theyll work their way back round. Youve done it fine :)

[luthor1]

that would only work if the number of teeth on the belt was an exact multiple of the number of teeth on the cam pulleys.

what you need to realise is that the teeth on the belt are a uniform distance apart. Now, remember that the number of teeth on the crank pulley is half that on the camshaft, so the camshaft moves EXACTLY half the speed of the crankshaft. Irrespective of the number of teeth on the pulley.

The belt is the correct length, but it's not an equal multiple of the teeth on the crank pulley.

Hope that helps.

Andy

[rwillis89]

thanks for the help! can continue putting it all back together now:P:D

[VTS123]

As said, they are just for the initial installation. I guess the VTS has them because, unlike the 8 valve models, the pulleys can be adjusted independent of the camshafts to which they are attached and ensures both the pulleys and the camshafts themselves are correctly reset for the new belt.