Well, a number of things may be causing the noise you describe. One possibility is the plastic distributor cover hitting the fan, (unlikely), others may be something rubbing against the timing chain, or a chain rail out of place. I would take a hard look at the possibility of something being disturbed or out of place during your reassembly. I say this because you state it started after you put it back together. I would take it down again and really take a look at the components up front. Could even be the distributor rotor being incorrectly seated on the cam nose or something loose inside the distributor cap. You will need to locate the noise. Open the hood, start from cold and really look and listen. If it's not an external cause, get a mechanics stethoscope and check the front cover, distributor, etc. Remove the oil filler cap and see if that increases the intensity of the noise. If so, then the culprit is under the valve cover. Good luck..
2000 Dodge Grand Caravan SE
No matter what you fix, there will always be something else to fix..
"Warranty" is just another way of postponing the inevitable.