my dart left me stranded

You might think I'm crazy but get the motor warmed up and adjust them while it is running. Put some news paper below the valve springs to catch some of the oil that will splash out. When you adjust them while it is running you are actually adjusting them at the state that is most important running rather than with a feeler gauge. I used to adjust mine on a chevy truck like that after I had the cam out or rebuild and never had to adjust them again. It was something like adjust it until you hear the valve tap and adjust it until it was gone and then another 1/4 turn or maybe 1/2 turn. It has been a long time.