Word for word by the non-USA vocab in the '75 Owner's Manual. However, the original carb had a choke breaker/ throttle positioner diaphragm, which makes it very automated by vacuum if you have such a properly set feature. Why LC never used electric autochokes in the USA is beyond my understanding, other than I guess the market was tech-phobic and they were resistant to keep up with advancement?
My 2F is below factory standards for vacuum, and it needs a rebuild. That said, I never 'pump' the throttle. The truck starts just by itself, then I feather in the choke butterfly in while I attempt to not get the rpms too high with some throttle. When you 'pump' the throttle, it makes unmixed gasoline go into the intake, these trucks run on fuel mist, not a gasoline siphon from a puddle under the carb. I might open the throttle if I predict what others call 'vapor lock,' but never on a cold motor. If the extra gasoline from throttle 'pumping' burns, I'd expect carbon mess if it doesn't have the time to fully burn, which isn't helping your ignition system. My ancient originalish starter has what it takes to pull vacuum thru a cold carb, and I'd rather it be kinda dry so I don't dilute my gasoline. Quick starting is all about correct timing (particularly not too early) and a clean spark that even the most primitive of Fs could fire.
Maybe because of my altitude, but, slightly choked seems to starve the main(nozzles) fuel circuit, and if I need full throttle, I get a kinda lean hesitation keeping up with traffic. If I push the choke fully in, it will idle rough at the intersection, and it needs to be pulled out a bit. Running with the choke butterfly anything but vertical isn't desirable for regular sustained warm motor operation in my experience.
The best way of getting most from cold-weather-driving, without opening the hood, is to fire it up for a brief time, then shut it down, it is like removing cookies from the oven before they are done, because they will finish as the sheet is cooling down. Ten minutes after an initial fire-up it is so much easier than if you just set-out on your trip without letting the heat diffuse for a while. Time for scraping the windows without listening to the motor or having to smell it. Plus, if you were to keep the motor running, you are just drawing (impressive in volume) super cold air thru the carb, until the engine bay finally gets warmer than the outside environment.
