questions on timing an engine

And yes it does seem to be running good where its at now, its running about 8 degrees initial and 35 degrees mechanical. tommarrow i might advance it all the way to 12 degrees initial and set it at 34 degrees at 3000 rpm and see how she runs there. or should i just leave it alone? I been trying to figure out why i cant advance it past 12 degrees initial? the vaccume canister is not hitting anything nothing is in its way it just does not turn any further. With it turned all the way i checked it and it was at 12 degrees initial. Is it possible my old man put it in this way so that it couldnt be advanced past 12 degrees?