Original 8 track in '75 Delta that experiences a " whirring" interference when accelerating. Anyone know the cause and cure ? Thanks !

 

Does the FM radio do the same? If so, then check the ground connections from the radio under the dash.
If only the tape player does it, then it is most likely an issue internal to the radio unit.

 

There should be a condenser on your coil! It's probably weak! Also, as mentioend above, check your grounds, especially make sure your antenna is tight!

Also poor quality, and/or leaky spark plug wires will cause it!