I'm confused about distributor advance specs. Also, dual point tech.

Hmmm. I happen to have an NOS (never used) CAP version of this same distributor (2642358, IBS 4013-B). I was wondering if it might be a good substitute. But then I looked at the specs. The vac advance curve is exactly the same. But the centrifugal curve is even steeper — it is + 24º to 28º @ 1560RPM. I suppose this is because the static timing was retarded, at 5º ATC. I don't have the CAP widgets, so I don't think it would be happy at that timing, and the curve problem would be worse.

I also have two examples of 2642461 IBS-4013-AS, which is not listed in my sourcebook, so I have no idea what the spec is. It is visually identical.

Oh, I forgot — Cuda Al explained this to me once. The final "S" just means it was sold as a part without cap & rotor. So these two items should be stock replacements for mine.