If more folks had grown up around an independent shop in the mid-1950's like I did, the design would make more sense. Ring/valve jobs came pretty often back then, and the top quality shops ALWAYS adjusted bearing clearances in the process of a re-ring job. It was not uncommon to do a ring job every 30-40K miles back then, mostly due to abrasive wear caused by dirt that got past the oil bath air cleaners of the day.
The adoption of disposable paper air cleaners and PCV crankcase ventilation systems that used clean, filtered air to vent the crankcase doubled or even tripled the expected life of the average engine.
Jerry
