Set "total" timing on a stock 318 two-barrel where?

dibbons said
Why are the factory specs for initial timing around TDC +/- 5 degrees and mostly everyone on this forum is setting initial at 10-15 degrees? Did the factory know something we don't?

While we are on the subject of timing, I will mention that I installed a Pertronix Billet Distributor #D141700 about a year ago. The instructions are very complete regarding centrifugal advance and how to customize it. The factory installed springs/limiters allow 5 degrees advance @ 1500 RPM, 10 @ 2000 RPM, 16 @ 2500 RPM, 22 @ 3000 RPM, and then full 24 degrees @ 3500 RPM and above. That is fine and dandy, but there is NOTHING in the instructions (or website) regarding the operation and specifications of the vacuum advance. I sent an e-mail question to them today in which I asked for specific information on the profile of the vacuum advance. I thought is was strange the vacuum advance was not even mentioned anywhere and to the best of my knowledge gas mileage can really be improved with a working vacuum advance.

The TDC or in some cases AFTER was for emissions. If you look up something like a 65 hemi, you get a much different picture. Bear in mind ALL engines 68/ later were emissions laden, starting in 66 in CA. Even the 68 340 stuff had a better curve than the later ones

So far as vacuum, that has it's own problems, because different carbs can provide different amounts of vacuum, and can cause ping at light/ medium throttle settings. And then you have (I believe it's) FBO who insists the ONLY way to run vacuum advance is at full manifold vacuum