1976 F-100 4x4 with a swaped in 390. Im not getting spark at the spark plugs. im getting 12v to the coil but when i hold the coil wire (the one that goes to distribtor) and ground it while cranking there isnt a spark. so my questions are: A new, but faulty coil? a bad coil ground? they are what i can think of, but how do i test to see if they are the coprut. Oh and i am running the duraspark system on it.

 

Check the dist rotor for turning and the rotor tab is touching the carbon point on the cap.

Plus check the pickup coil in the dist as it sends the signal to the coil to fire.

 

Maybe i wasnt clear in my posting... im not getting power past the coil... as in, to the distributor.

 

and that is why I responded like I did .

The pickup coil pictured above.,,,sends a signal to the Ignition coil to send a power spike through the secondary ignition circuit ( Coil mast back to the dist)

everytime a stator vane passes the PU coil... it sends a signal to the IC

Quoting a photo is unnecessary.

In fact quoting on the 1st reply is unnecessary

 

So, the pickup coil (the blue covered thing in the pic), whats the secondary ignition circuit? (like a condincer only on the side of a coil?) sorry im a total nube to eltronics and cars

 

How are you checking for spark???????? Are you lifting the actual coil wire, and turning the engine over?? If yes, you will never get spark directly from the coil. The coil is nothing more than inductor. The coil is going to require a set of points or other solid state device to store, and create voltage.
Might have a bad module in your duraspark system. This is probably not breaking the current to the primary coil, and it simply can't produce a differential change between the primary and secondary windings, and never produce voltage.
If it was a points distributor, it might be the points, since it is not, then the solid state device might be the problem, in this case the duraspark module. Would check what Dennis suggested first though.

 

Primary circuit is 12 volts at start up...6-9 volts in run

Secondary circuit is the HIGH energy (15,000v-18,000v) that goes to the plugs.

The negative terminal on the Ignition coil receives the signal from the Pickup coil and triggers the Ignition coil to fire a Bolt of Power back to the distributor cap to distribute it to the spark plugs


Picture.

http://autorepair.about.com/cs/gener.../bldef_340.htm

Ignition system explained

http://autorepair.about.com/cs/gener.../aa072200a.htm