Timing Puzzler

Yes, in the "good old" days of "smog" there were engines that called for timing of 2BTC, ZERO TDC, and 2 AFTER TDC

This does not mean that's where you should set it

One caveat--if the engine still has the original distributor, some of those had a very long, very slow timing curve, which means that if you just bump it up to 10 ore 15 it might OVER advance at high RPM. So you need to check and see what it's actually doing, and as old as that is, might not even have the original dist.

Also look for, and consider bypassing any vacuum controls in series with the vacuum advance. The great state of CA, before I left the U.S. Navy down there, was forcing people to add bright green thermostatic vacuum controls to their engines.