The variability in timing because of shafts being out of true, incorrectly machined cam lobes, worn bushings and anything else I've forgotten about, is why I don't try to get the last possible degree of spark lead out of my setup. It's a 261 with an 848 head, which going by published C/R figures should net out to about 9:1. I figure that's about the limit for 87 octane gas at sea level. I run regular gas. Off idle behavior tells me I could use a little more initial advance and the cam I use would indicate that. BUT I don't hear very well and I'm not confident I could hear spark knock. I have burnt a piston on the past engine so that's certainly possible and I don't want to push the issue. So, I static time the ignition using the BB and the U|C mark and the vernier scale on the octane selector. It runs just fine with the points triggering the MSD capacitive discharge ignition.
Even after all these years I still don't have a delay timing light nor a Sun distributor machine so it's largely a seat-of-the-pants affair but I've got away with it for 50 years. That said I doubt that the original poster's problems are related to ignition timing unless maybe the advance mechanism is totally frozen and since he's using a Pertronix dizzy I doubt that's the case.
I don't know if Pertronix units are capacitive discharge (CD) but my MSD is; and an artifact of this design is that the voltage rise time is much faster than a Kettering (battery and coil) system. That effectively means that there is more advance built into the system. So to have the factory total advance, you'd have to set the initial timing back a few degrees, which, If you have a long overlap cam, will cause a lag off idle as you're pulling off a stop sign or whatever.
Is it possible to assemble the advance mechanism backwords so that rather than advancing, the unit retards as RPM goes up? His discription of the symptoms sound like that might be the case. Were there any Delco Remy distributors that rotated the opposite way from Chevrolet? Could parts from such a dizzy, if one exists, have gotten mixed up on the bench or parts box and ended up in his dizzy. Ah, but it's a Pertronix so that possibility is out the window. I have to say that either there's missing information or the heat has gotten to my brain -- 100 again today.
