Sorry for the lag time in reply...sometimes work gets in the way of play.
Just to make sure I understand, the idle speed slows not immediately after pushing choke in, but at some point later when engine is fully warmed?
Just throwing crap at the wall here....maybe something to do with the manifold heat riser closing? Not real sure why that would change idle speed, but it would be a common element in the engines with two different carbs.
Yes, your understanding is correct. Choke all the way open idle speed at approximately 5 minutes run time is faster than choke all the way open idle speed more than after 30 run time (after actually driving, not just sitting and idling).
You may be on to something with the heat riser. Both vehicles do have functioning heat risers.
Carl, idle is smooth with both conditions. No performance issues on either, they actually operate surprisingly well for 1930's technology.
