Verify the timing marks on the dampener and timing cover to make sure that TDC on the dampener is zero on the timing tab on the timing cover and go from there Let us know what you find I have a B motor in the shop now that a customer was running(it didn't run very well) that has a early straight tab timing cover with a later model stock dampener, that combination throws the actual timing of by over ten degrees, if you use the zero mark on the timing cover tab