checked the schematic - my tach works intermitantly.....

Ok, its running... Switched the blk/wh to a different spade on the coil.... Bad connection? This car has pertrononix, so wiring is weird. Theres one blk/wht directly to coil, another to the bottom of ballast. Theres a red wire attached at bottom of ballast that leads to dizzy. Top of ballast connects to grn/white that goes to front of car?? Coil reads 12v when running.

Since the wiring is non-stock, it's not clear where the blk/wh was originally.  A schematic of your car's wiring as it is now would help.

now its not running again - pos coil is .6V in on position.

 

checking the schematic, it looks like the pertronix is taking power from the line running into the ballast resistor. 

 

Here's the schematic

 

Maybe the pertronix igniter failed

pulled the steering cover and pulled the ignition switch plug - tested continuity:

 

green/white - closed circuit - good

 

BLack/white coil and ballast -  shows resisitance for just a second then open line...... ??  broken wire?

OK, ran a lead directly from the battery to the blk/wht terminal on the ballast resistor - car runs.  still not continuity between the b/w at the switch to the ballast terminal.  So, i've got a bad line from the switch to the ballast - any ideas where that might be??

Are you sure it's not the switch itself?

petty sure it isnt,  there's no continuity between the b/w wire at the switch and the b/w wire at the ballast.  I can run power directly to the b/w wire at the switch to test it tho.

pulled the b/w wire from the ignition switch, connected directly to battery - same issue car runs in start position but not run position, so its not the switch.  OK, added a jumper (red) from ig switch to ballast and car runs fine.  so i've definitely got a bad lead between the ig switch and the ballast resistor - any clues/hints/ideas where that might happen? Or does anyone know where the line splits?  ( as a bonus there are two indentical b/w leads heading back from the coil! )  So, i know what the problem is, i just dont' know where the problem is!

 

Try to inspect the BW wire where it enters the harness and where it comes out. Could be a rodent chewed through it or corrosion or maybe just melted in the steering column.

 

Check continuity and resistance of of the suspect wire from the IGN Sw. to the ballast.. An easy way is to pull the Battery positive then measure the resistance between the new red wire and the BW wire at the IgN. SW.

 

Also check to see if +12V is at pin 2 of the IGN. SW when in Run.

the switch is getting power - it runs in "start" position and also when i connect the red jumper below.  i've checked switch to ballast - no continuity.  cant see anything wrong with b/w wire, but i cant see most of it.  anybody know which fuse b/w wire connects to at fusebox?  i could check continuity there to narrow down the issue.

 

problem solved.  The discontinuity was inside the spade connector at the ballast resistor!  I cut the spade connector off to start tracking the B/W line back into the harness ( i untaped the whole front  of the harness ), and i thought "hmm let me check continuity on the bare wire".  Sure enough, there it was.  I had checked that both wires ( one to the pertronix ) were tight, but somehow the current wasnt flowing into the spade.  So, put a new spade connector on and voila........  no clue how that works.