All I know of is there are 2 differant sizes of dampers....6" and 8"
and all the SBC's I have had work on, they all pretty much lined up between the mark and the keyway....afterall the keyway is 3/16/close in width, so takes your pick....:crazy: :laughing:
I not aware of the timing marks ever moving on the chain cover, or any aftermarket ones....otherwise, how would anyone ever replace a balancer?? have to know which crank/etc was in the engine/etc....not possible to do...
They changed the location of the timing mark in relation to the keyway in the late 80's. FOund that one out the hard way. Don't know why they did it, maybe some cars the pointer had to be in a different spot. Maybe because of the serpentine belt? But they are different. Interchangeable as far as balance goes, but the timing marks are in different places.
That's what I recall. Early stuff the keyway and the mark were really close. Stick the balancer on without the timing cover, just enough to catch the key, with the timing marks on the cam & crank either in the #6 or #1 position, hold the tab up there and see how far it's off, if it is.