AS base caliber info for Bulova BII from the 1920s

[Dmitry]

I am playing with a 1920s Bulova BII caliber, and after two donors I am looking to break the unlucky streak with hairsprings. I understand that the BII caliber was based on an early AS, but I cannot find any references to what that base caliber was. I am hoping to find a complete balance assembly, or at least functional hairspring that is likely to work with my caliber. The art of vibrating hairsprings seems to be no longer practiced:(

Here is a view of the BII caliber, any info is highly appreciated:

https://www.ebay.com.au/itm/385387448204

Thank you.

[Nucejoe]

Hi ,

Check DoRoWe 202.

 

 

[JohnR725]

1 hour ago, Dmitry said:

1920s Bulova BII

The problem with something like this is the cross reference books don't really exist in the 20s. The bestfit book and others are more like sometime in the 50s up until the mid-70s and anything before the amount of information becomes problematic.

Then there is the other problem with your eBay photo graph we can sometimes do identification of watches with the setting parts conveniently hiding under the dial.