So I have a 69 Mustang with a 351 that's been sitting for a while. I tried to crank it recently and can't get the engine to "catch." I've got new fuel coming in (and I spray starter fluid down the carb), a battery with 12.75 volts that turns the engine fine, 150+/- psi in the cylinders, but I can't get a spark from the plugs (I lean it against the intake manifold to ground it when I check). I have a distributor that's rotating, new distributor cap and rotor, new plugs, new plug wires, new coil that tests within specs for ohms (primary and secondary coils) and 10.48 volts into the coil, but still no spark when I put a plug+wire into the coil output and ground it to the motor. What am I missing???

 

Ignition high voltage is very easily misguided to ground by a number of factors sometimes hard to locate. First, make certain the INTERIOR of the distributor cap is perfectly dry, and rule out the possibility of a hairline c rack in the plastic wall grounding out the center electrode to the distributor base; try another cap. Check that the ignition coil's secondary is not SHORTED TO GROUND: there should be infinite resistance between the top ign wire connection and the outer case of the coil. Lower resistance there indicates a short to ground, possible even in a brand new coil. Replace the high voltage wire connecting the coil to the distributor cap.

Have you checked the dwell, or the fact that the ignition points are actually turning the coil on and off?

 

So thanks for the reply, here are a couple thoughts:
1) I (believe) I have a Pertronix ignition system vice points. I replaced the Distributor Cap and rotor earlier. No spark on the plugs (both old and new)
2) I have 1.2 Ohms of resistance on the secondary (post to post) coil and 12230 ohms on the primary (center to side post) coil. Those numbers should be in spec
3) As a "cheat" and to isolate the problem further, I pulled the connector that goes out of the top of the coil and into the top of the Distributor cap, put a new plug in the end of that line and properly grounded it against the intake manifold to see if I had spark there--I did not
4) I have 10.95 volts coming post to post across the coil, but no spark coming out
5) I've replaced the coil and had the same results with a new coil

SO WHAT AM I MISSING!!! UGH