Having an issue keeping the choke on when starting on cold days. When the choke is supposed to kick in, I press the gas pedal one good time and it fully closes. But, the next time I hit the throttle, the choke opens back up, regardless of the engine temp... Literally, even if I hit the pedal, choke closes, starts up perfect with high idle... Then I give it a little gas to back out of the garage and the choke comes off.

Any ideas what's causing it or how to troubleshoot?

Carb is a 4bbl Holley

 

Remove the black choke unit, and make sure the tab on the choke linkage arm is on the correct side of the tab on the coil spring. The spring tension should be holding the butterfly closed till it heats up from the power going through it, and unwinds it. It sounds like the butterfly is being allowed to flop freely. If that part is ok, could be your choke unit has gone limp, and a replacement could do the trick.

 

Now that its cold again, I'm playing with this choke issue again. I adjusted it cold, with the key on and it sits about 1/8" away from closed when cold, power on and pumping the gas once. Within a minute, the choke is hot and the spring opens. Should it stay open longer than this?

 

You never said if this was giving you running issues or not, or if it's just an observation?
The choke butterfly shouldn't be opening that quickly though. If your engine's needing to be choked for a longer time,
adjust the spring to close the butterfly more by rotating the black cap counterclockwise.

 

My experience with automotive chokes is ,the shorter time the choke is on the better. I dont know exactly how many minutes your choke should be on,but it should only stay on long enough to give your car the ability not to stall or backfire,once the motor has a little heat in it your choke should be off or open. ed

 

It's definitely running a little rough from the time it first opens the choke and the time it's warmed up. I played with it a few times today but, took too long to cool between test runs. In 35* F weather, should the choke open completely vertical when fully warmed up? Or, when its this cold, is it ok to stay a little bit closed? After the final adjustment today, it started good, idled well and took a few minutes to get the choke around 79-80* open... It never opened to completely vertical or, 90* from horizontal.

 

That type of choke isn't tied to the engine's temperature. It works by heat generated from the power to it making the wound spring inside the cup move. So if you were to turn the key on (engine not running), the choke would still open. You probably are, but make sure you don't have the key on for a period of time before you actually start the engine. Doing that will give you some lost choke time for the engine to use. And yes, the choke butterfly wants to be vertical when it's done moving. Did you check to make sure the butterfly linkage is all connected right, both externally and inside the choke cup?