[Sirrotica]

Greg, as Shurkey has referred to the mass of cast parts of the hot air chokes keep the choke from re-applying as quickly as the electric ones do. You might need to find out what carb the electric thermostat comes on, and use those specs instead of the OEM 74 specs.

The quick cooling off of the electric chokes is why I usually try to use the engine heated chokes on my own cars. I do however remember working on a few of the electric chokes in the dealerships where I worked in the mid 80s and those cars didn't seem to have the common problems associated with electric chokes when doing a conversion from engine heated to electric. That might be attributed to different specs for the choke pull offs, and high idle specs.

The magnetic choke angle level gauge (pictured in the chevelle article) was used on most of the later carbs, instead of the drill gauges to set pulloff opening. That could be a problem when converting to the newer specs if you decide this might be the key to your problem. Most people that don't work on carbs for a living wouldn't have that tool at their disposal. I happen to own a Kent Moore carb gauge set of tools, but the average Joe isn't going to have the set. I'm sure you could buy the magnetic choke angle gauge separate though if you googled it. GM/Rochester decided that the choke angle gauge was more accurate than just using drill gauges during the closing years of carburetors.