Issue with 6A box.

[84 4+3]

Good morning all. I have an issue with an older model 6200 6A box on a '67 Firebird running a converted HEI distributor. The problem is that upon switching to the box, I can no longer run my vacuum advance. I've confirmed that switching back to the in-cap coil without the box it'll operate as it should, so I'm wondering what all could be wrong.

I had placed a phone call a few days ago and a tech seemed pretty convinced at that point that it could be an issue with the box, but that I could also try reversing the pickup leads. Now I know this does cause my timing to read ridiculously advanced as I tried it. But reading through the tech articles, it'd seem that the proper way to setup the box is to go with the more retarded reading. From my memory I saw something like 50° of advance with the coil reversed on a dial back. (I know, but my good light wasn't on me at the time. I have an old analog Matco one that I'm using now.)

Should I try reversing the coil leads and then adjust the timing? It seems to me like a phase issue once the vacuum advance comes in because it just starts bucking like a cold start on a diesel with any crack of the throttle on port advance. If I pull the line it runs fine, but I have confirmed the engine would prefer some vacuum advance at cruise. It brings temps down quite a bit. Any input is greatly appreciated. I just wanted a second opinion before I started messing with parts.

[Danny Cabral]

Originally Posted by Danny Cabral MSD Magnetic Pickup Polarity Testing: If you’re not sure about the polarity of the pickup you are using, there is a simple test you can perform by checking the engine’s timing. Check the timing with the pickup wires connected one way, then swap the wires and check the timing again. You will notice that the timing changes significantly and may appear very erratic. The correct connection depends on the ignition control that is being used. Read page 2: https://documents.holley.com/techlibrary_pickups.pdf (MSD Magnetic Pickup Testing) Analog: If using an analog controlled MSD 6A, 6T or 6AL series, SCI series, 7AL series, MSD 8 or 10 or Blaster Ignition, the correct connection is when the timing is retarded. Digital: If using an MSD Digital-6 or Digital-7 Plus, or the Programmable Digital-7 Ignition Controls, the correct connection is when the timing is more advanced.

[84 4+3]

Thank you. I knew I read about it I just wasn't sure. I'll check it out later.

[84 4+3]

Not really sure what fixed it. The way the pickup was wired it was correct. First try, it didn't work. Then messing around for a bit it just started working. I'm just going to assume it was some weird issue.