This one really has me stumped. When checking timing I see that the timing mark on the damper is bouncing. If looking at the damper as a clock, the mark is every between 7 o'clock and 11 o'clock. When it bounces to 11 o'clock it at 10 degrees where I want it. The motor is a rebuilt 361. I already pulled the timing cover and checked the chain and it is good and tight, no slack when I rotate the engine by hand. I also pulled the distributor and the for slack in the shaft to shaft. looks good there. These are all new parts. Any ideas out there? Thanks,, Alex