another thing that can help the situation is to open up the idle feed restriction in the secondary metering plate. the old bulletins say to open this up to .070"; that's a bunch considering it's probably .036". I would try this to help compensate for the primary side but I don't think i'd jump to .070" if I was doing the primary side mods. going to .40"-.045" would make a noticeable difference in area.
If you clicked on the first link Mattax posted there are some good pics of the baseplate.
I don’t know if all of this list number carb were the same as that one, but that carb had no actual secondary “idle” circuit.
There were only some slots/feed holes positioned well above the throttle blades....... so they contributed no additional fuel at idle....... so making the feed restrictions for that circuit bigger shouldn’t have any impact on the idle a/f ratio.
In one of the other links where another person was playing with one of these carbs, they also referred to the lack of that circuit, which is also used to keep the fuel in the secondary bowl refreshed.
