Ford fitted a number of different ignition systems to the Sierra's, work out which is yours from the following diagrams etc.
Pinto fitted with ESC1
Pinto fitted with ESC2
Inductive (In my opinion the easiest to work with)
Ignition timing out??
If you've ever been messing with the engine, either with the dizzy or camshaft etc. Then it won't start afterwards, you then start to think, "Have I got it 180º out??" you then start either guessing, or having to take off the rocker cover to see which valves are depressed.
Here then is a little help. If you put the crankshaft onto the TDC mark, and the cam timing pointer is showing above the top of the rocker cover, then you are at the point of No4 cylinder being at the firing point. So your rotor arm should be pointing to No4 HT lead. If it's not, then you can either do the quick change, by swapping over HT leads, 1 with 4, and 2 with 3. or alternatively, by removing the distributor and refitting it.