Help! no spark to plugs will not start??

[doncarson]

Hi All;
My Cuda was running fine. I needed to replace the alt. because of a stripped adjuster threads. I put the new alt in and now the car will not start.

 I checked all I can with no luck. Car has a MSD 6al box, Mallory promaster coil, stock electronic dist.

 I did the green/purple jumper test and I get good spark from coil wire. I get only about 4 volts at coil (+) side when cranking. No voltage with ingition key at run position?
What do I look at next??
Thanks!
Don

[Chryco Psycho]

check the gap in the dist to be sure the dist is signaling the box to fire the coil , the gap should be .008

[doncarson]

Hi Chryco!
I checked the gap and it's .008.
No spark to plugs....
 

[Changin Gears]

You could try to "hot wire" it.  Run a wire directly from the battery + to the + side of the coil and try to start it.  This will tell you if it is a power to the coil problem.  Remember, to shut the engine off you must remove the wire.

[doncarson]

Are you sure you can do that with the MSD 6al and promaster coil? , I tried that and the jumper wire from the + battery terminal to the plus side of the coil (with the original + wire disconnected from the coil) it started to get hot and smoke (only about 3 seconds)!

  If I should be able to hot wire the coil, it seems like there is a short, where should I look?

[Changin Gears]

It is a  normal condition to apply full battery voltage to the coil for a short period of time, this is what happens when you turn the key to crank.

It sounds like the coil itself is shorted.  Do you have another coil you could try (stock or anything else)?

[doncarson]

Thanks Changin Gears.
I do have a coil on my 71 Demon race car w/ MSD set-up. I will swap it out in the am and see if that's the problem.

Don

[doncarson]

O.K.
Replaced the coil. Still will not start. Jumped a hot wire to coil from battery, still will not start. Tried the purple brown jump spark test again and good spark.

. Removed the dist and turned it and I get about 1 volt each pass of the reluctor measured at the trigger wires.
. I connected the dist but left it out of the block, turned on the key and turned the shaft and got a backfire through the carb from a cyl that must of had the intake valve open.

 It appears the dist and ign is working. Put the dist back in the block and STILL WILL NOT START.
I put some gas down the carb and it cranks over O.K. but not a single fire?
I'm LOST???
Any more Ideas.
Remember it started three days ago. changed the alternator out then will not start.
What am I missing?
Don

[Changin Gears]

Have you checked for spark while cranking?

[doncarson]

I took off a plug wire and held it 1/4" from a ground and NO SPARK.  But why when I spun the dist out of block did a get a spark?
I checked the rotor and its turning and cap and all look fine no broken pieces or anything
?

[Chryco Psycho]

That makes no sense , you doi not get a spark when cranking but spin the dist by hand & you get a spark , the only thing I can think of is the red trigger wire to the MSD has to be connected to both the blue 12 v run wire & the brown start wire at the ballast resisitor connection to get spark while cranking it

[doncarson]

I just don't know what to do. Everything looks as it should be... This is crazy....
Like I said before I hooked everything up but had the dist out of the block and when I turned on the key and turned the dist by hand I got a spark and backfire through the carb.
>>>>>>>>

[Chryco Psycho]

Then it has to be the smaller red MSD wire that has to be connected to the brown cranking power wire @ the ballast plug , if it is not connected there there is no power to the MSD box while cranking

[doncarson]

I did not change any of the wiring and all looks as it was. I also hot wired from the battery + to the coil+ and cranked and it did not start???
Still lost and confused.........

[Changin Gears]

You could try pulling the coil wire out of the cap and see if the coil is firing and the problem is in the distributor.