Question...what is the normal running temp for a 1972 340

Keep "the radiator" in the back of your mind. I had a 360, now a 318, similar problems with the original 67 273 rad, and the "rad guy" claimed it should cool

A couple weekends ago I decided I'd had enough, threw an unknown SLANT SIX rad in the car out of a 73/4. Hell, the thing is night and day. The needle "runs" as far below 1/2 scale as it used to above (I have a 180 stat in the car).

Oldmanmopar posted something a few weeks ago, a theory that something (heat cool cycles?) eventually cracks the fins loose from the tubes, reducing heat radiation. In other words it can flow lots of water and still not cool.