I just bought a 1966 Mustang with a 200 CID 6 cyl. The timing mark on the damper is way off of the timing marker. I have replaced the distributor with a rebuilt. Reset the dwell to 40 degrees. Reset the idle. And I am using a timing light. If I try and adjust the timing to get it to the 0 degree mark the car runs horrible and stalls. It runs ok where it was. When using a timing light the mark on the damper is about 60 degrees retarded. Hence-- I cannot set the timing correctly not knowing where it is. The timing is just where it was before the new distributor, the problem is exactly the same after installing a new distributor, resetting the dwell, idle and using the timing light. I reinstalled the distributor several times and got the same results. I put in the new distributor with the piston at TDC and checked the distributor location. The engine runs good even though the timing mark is way off the indicator. I dont know all work the previous owner did other than install a new carburetor and some valve work. Your help and ideas is appreciated.