The later A12 engines seem heavier than the early dizzie units but
Im not sure on the a12a but which confuses me as Ive read early blocks
are supposed to have more casting material than later?
Cost cutting measures are definitely there on A15 blocks as they
seem to develop corrosion on the walls that affect overbores.
Ive seen A12 engines go to 78mm with no issues at 10k rpm
but A15 engines going to 5mm overbore dont seem to last
without developing pin holes on their bores.