Auto lite distributors?

[1909schacht]

Have this odd 6 cly auto lite distributor 

1BA4001 5H

with adjustment instructions on what appears to be some sort of case extension 

not sure what the extension was used for - have not taken it apart ...tempted but not yet

Any ideas ?

[drwatson]

Late 1927 Essex Super 6.  (Google)

Edited June 26, 2017 by drwatson (see edit history)

[broker-len]

noticed the timing instructions      is'nt this called power timing