[MagmaJct]

Wow, a lot of good info here. I'll just respond to all in one post.

The distributor has a points replacement module, similar to the Pertronix. (It might very well be a Pertronix.) It's been awhile since I verified the dwell, I don't recall it being out of spec. I can't seem to find how to adjust it anyway. (With the lack of points, that is.) The timing stays steady, I can check it weeks later, and it'll be where I had it last. I will mark the damper/pulley to verify it's not slipping. Good idea!

Regarding using a vacuum gauge to set the mixture, that hardly works. There is very little change in vacuum regardless of whether I use the Qjet or the AFB. I just reinstalled the AFB in the interim, because it idles better with low vacuum. I set mixture by best idle RPM, then back it off ~1/2 turn.

Best vacuum at idle in neutral is 13 "mg, 10 "mg in drive.

As far as I know, the truck does not have a performance cam in it. But hey, I could be wrong!

I agree that advancing base timing isn't the way to go. Those were initial tests.

I intend to pull the timing cover. But that kind of exploratory surgery will have to be scheduled. I'll keep this thread and post my results when the time comes.

Regards,
Mike