OK.. I can narrow it down for you....
The presence of the spark after you turn off the ignition confirms:
- The coil is getting 12v + from the ignition.
- The coil is serviceable.
- The negative wire from the dissy to the coil is grounding.
Hence the reason you wont be getting spark is that the negative supply to the coil is not breaking when the engine is rotating.
Just incase your not sure on how the coil / ign works heres a overview:
- The ignition is turned on, and the coil is suppled with +12v on the + side.
- The negative side is currently grounded, and the coil is energised.
- As the engine turns, when a spark is required the negative side of the coil is suddenly open circuited (ie not grounded anymore). This causes a mag field change in the coil and a spark is produced.
Now comes the tricky part:
- There may be a second wire going to the negative side of the coil (somewhere in the loom of the car) which acts as an immobiliser. By being grounded, it prevents the negative supply from the coil breaking and hence spark.
If there is such a wire, disconnect it and see if she fires up.
If there isnt, there must be a fault with the distributor itself. How does the distributor operate? Is there points, hall effect, or reluctor??
Its likely that the inner workings of the dissy have failed. Without knowing the specifics, I cant recommend a repair option.
Hope this helps, sorry if its a bit confusing