1972 dart - stopped running while at 50 mph ? no warning

67Dart273 said
Let's try it this way. You may not have hot enough spark. Jumper power to the coil direct. By the way do NOT leave this connected any longer than necessary than to make the test. If the engine fires and runs, you can leave it connected for a minute or two. This is hard on the coil and points

Now with the jumper connected, crank the engine by using a screwdriver between the two bare terminals on the starter relay, the "big stud" and the "big square" terminal"

Now you can see the spark and see how good or how bad it really is.

I am "assuming" this because you say "no spark at plugs." The rotor, cap and wires do not look too bad. The only thing left in that mix is the coil wire. You can check it (and the other wires) with an ohmeter

ok i did try to start it that way earlier , with a remote starter switch , no start . i will try the spark test again this way , another day .

yes i tested coil wire ... it is getting spark ........ next tested resistance of the coil to cap wire , but could not get a steady reading . it would just flash a number briefly before going back to 1 , but flashed anywhere from 565 to 998 . so i got the 74 valiant slant six started up , and after a short warming . took out its coil wire and put the darts in there . the valiant ran , seemingly just fine . i did not try the valiants coil wire in the dart , because i don't want that to get screwed up by whatevers going on with the dart . just paranoid probably , but not doing that . i checked the resistance of the ballast and got a reading of 1.7 and 1.8 , but , again , not sure what that is supposed to be .

i will test the other wires too . what should they read ? also shouldn't there be little sparks at the points when the engine is cranking ? there was not , they were opening and closing and i got a dwell reading . i am thinking something with the dist. maybe . rotor and cap and points are new or a few months old . wires and condenser are somewhat older .