Originally Posted by indianaman
Sorry for the long post but I think I may have messed up. I needed to replace my timing belt so I tore her down got off the harmonic balancer then put some green paint on the belt and the crank. Some blue paint on the belt and exhaust cam. then some Orange paint on the intake cam and belt. REmoved the belt counted the ribs between old belt and marked new belt with paint on same ribs. i.e from green 60 ribs to blue paint then from there 15 ribs to orange. re installed belt aligning paint marks perfectly. set tensioner. now when I rotate crank the paint marks never align again unless i rotate it back. I.e rotate crank ten times CW then back ten times CCW paint will line up no prob. am I good to go? car ran fine before I tore her down. Just some PM. I also noticed the tensioner moves off of its alignment markings when turning the engine over. is this normal. Its midnight and I am freaking out. HELP
ETA the car is still in pcs. now should i stop and get the stuff to put it at tdc? my new belt is on and my paint is still aligned.
The reason the marks don't continue to line up after rotation is that the number of teeth in the belt are odd and the number of teeth on the pulleys is even. 40 on each cam and 20 on the crank with 129 teeth on the belt. This is intentional by design so that each revolution of the belt around the pulley set touches in a new position thus minimizing the wear that could be caused always laying on the same teeth. This is common practice in gear train design as well. It all comes down to mathmatics and the least common multiple of the teeth numbers. To put it short it would take several thousand revolutions before your marks would all line up again. Or a few minutes at idle.