Ok so all of the sudden my 79 decided to not start but runs great
I know your saying how does it run simple roll start and it fires right up
It has nothing to do with hot or cold and sometimes it will start with key but most times it want
No sorry it turns over fine but never cranks you get it rolling and fires right up drive it 60 miles at 65+ and it never misses a beat
Shut it off sits few hours go out to start it up and again turns over want crank
First, check your fuses. Make sure they are all good.
Pull a plug wire and check if you are getting spark while cranking the engine with the key.
If you don't get any spark try the below.
The starter solenoid has a start circuit that is separate from the run circuit. If the start circuit is bad the starter will turn the engine, but no spark will get to the plugs.
Replace the starter solenoid. Check the wiring at the solenoid.
If the solenoid and wiring are ok, replace the duraspark box with either a junkyard find or from a parts store.
When you crank the engine and the starter is turning, the DS box sends a signal for starting (retards the timing, iirc) to help make it easier to start. If that circuit goes bad it might crank but not start.
If neither of those work then you might have to change your starter switch (the part with the key in it). The switch is separate from the keylock so you can replace it without having to make a new key.