Not to nit-pik, but, the early automatic choke uses engine vaccuum from a small port in the carb to suck heated ambient air thru' a tube from the heat stove, into the choke housing, past a bi-metal coil that then relaxes to let the choke open.
Of course it might be fair to say it works just like the heat stove on the '63 up sixes that have the bi-metal coil on the manifold like the V8s.
Or I just might be wrong again.
Tim
