FWIW:
A Ignition Timing:
1. Confusing to some, with engine rotating, no.1 piston reaches TDC twice.
2 Once when timed correctly, and once when 180 out of correct timing.
3 Next, if one loosens the screw on top of the distributor shaft, one can easily rotate the distributor cam and rotor 180 degrees, 137 degrees, 19 degrees, 7 degrees, or what ever.
4 Proper timing occurs when spark handle is upwards with spark retarded, timing pin slips in, and no 1 plug fires ... so simple ..... really doesn't matter if the rotor is pointing northeast or pointing towards the north pole.
B Valve (Fuel) Timing:
1. Valve (fuel) timing has to be coordinated with ignition, (spark plug), timing to supply a fuel mixture to be ignited at a proper time.
2. Valves sticking in valve guides slows down valve up and down movement and prevents valves from opening and closing at proper times; hence, a spark plug can fire when there is no fuel in the combustion chamber causing the engine not to start
3 Depending on different outside climatic conditions and different inside garage climatic conditions, changes in different temperatures and different humidity in different areas of the US, condensation moisture can easily and quickly form on metal in some areas, thus causing ferric oxide, (rust) on valve stems and in valve guides.
4 Again with different climatic conditions, when rust is combined with evaporated petroleum materials, (gas & oil), sticky varnish can easily be present to impede the up & down motion of valves; hence, now the fuel may not be timed correctly to be coordinated with proper ignition timing.
5. Some have difficulty understanding that in some different areas of the U.S & World, and in some different storage garages, a Model A can easily acquire oxidized points and sticky valves when stored for just one (1) year.