[Arran]

I believe that the old style molded mica caps had a tolerance of + or - 5%, and since the values were usually posted right in the service data, either on the schematic or on an included parts list. Of course they also included trimmers, and padder condensers in series with, or in parallel with a coil to compensate for the variations in manufacturing tolerance between one coil and another, some would take shortcuts though and use fixed micas rather then trimmers. I've never worked on a Philco superhet of this era, but I have worked on RCA/G.E/Westinghouse sets, and it is possible to get the alignments on those almost bang on in terms of dial tracking.
Regards
Arran