I have greatly improved the performance of my 1978 C3 Corvette 350 with automatic transmission. I am happy with the car now but the work I did has brought about questions. The initial advance with vacuum advance hose disconnected and plugged is 16 degrees BTDC and that setting is fine as time has proven. Now we go to mechanical advance that is set with the appropriate springs, weights and plate to be all in at 2500 RPM and 20 degrees mechanical advance and this is fine also. The issue I have is all of this advanced timing is BTDC. It is difficult to check the timing beyond the 16 degree initial because the timing mark on the damper disappears - meaning if one stands at the front of the car looking down at the damper and the damper is turning CW it would be noticed that the damper timing mark will move in a CCW direction as engine RPM is increased and therefore not visible and out of sight for the timing light. Something is screwy here and I am not seeing it. Thanks for any help !