Classic/Antique Car Repair: 1967 GM 2.5L engine, center terminal, coil wire

Question
I have this GM  2.5L 4cyl engine in a boat[mercruiser120hp] and have an ignition problem.  The motor has the point and condensor setup.  Having a spark problem.  I get power from both sides of the coil, but not from the center wire to the cap.  The points are hot [tested with a probe] but no spark from the coil to the cap.  The plugs do not fire[no spark] tested with an inline spark testor. It could be that the top of the roter is not touching the cap-I will check in the AM.  The roter and cap are in good shape.  Any thoughts.  Thanks

Answer
If you have a test light or a volt meter, put it on the negative coil wire (the one that goes into the side of the distributor) and with the ignition on, slowly rotate the crank.  

You should see the voltage pulsing from ground up to around at least 4 volts as you rotate the crankshaft, twice per revolution.  

If you do, and there is still no spark at the center terminal of the coil, either you have a bad coil or the condensor has failed.  

If you do not, either your points are not closing (in this case you would only see 12 volts on your meter, no pulsing) or they are not adjusted right (there should be a gap of around 0.017" when they are as open as they get as the shaft turns). If you can see that they are making contact when they close, but you still see 12 volts on the - wire, then the points are dirty.  Get a point file and clean them -that will be only a temporary fix, however, you'll need new points and condenser soon.

Dick.