1957-1958 from what i can find im about to give mine an overhaul its in bad shape.
Mossberg model 346 KB
Mercury model KB-!A motors where made in 1941. This model was known as the Deluxe comet.
Kb=1.62 * 10-12
Kb = 3.8 10-10
Kb = 55 It is a very strong base therefore it completely dissociates.
We would use a modified or full choke, and #4 shot.
The KB value is listed below: pKa + pKb - 14 pKa = -log10 (Ka), Ka of acetic acid = 1.8*10^-5 pKa = 4.74, pkb = 9.255 9.255 = -log10(Kb), Kb = 5.56*10^-10
It is a weak base.So pH depends on Kb value.
No published sn vale; 15-125 USD or so
There are 0.0198 Mb in 19.8 KB, But if you calculate it with the more accurate 1024 value => 0,019335 Mb