Holley 1945 /6 choke opening too fast?

[Loggato]

My Duster has an issue when it's not either just started or over 70 degrees outside. It wants to stall out everytime I give it throttle. When I pull the air cleaner off, I see that the choke is open all the way. If I close it part way, I can get the engine to rev clean. Is this perhaps an issue with the choke spring? or is it common for the choke to be open completely shortly after starting the car?

 

[toolmanmike]

Sounds like the choke needs to be richened up a bit.

 

[Garrett Ellison]

It's probably that choke rod needs the bend in it adjusted to put more pressure on the choke plate.

 

[440fury]

I had a similar problem with my slant 6. I wound up purchasing a new choke thermostat and bending the rod until I could start cold. IIRC they are pretty cheap ($20 ish). This got me to "good enough" but I pulled the engine before I had it completely dialed in.

 

[AJ/FormS]

At 70*F that spring should unwind PDQ, in fact it should be almost limp.
If the engine idles ok after warm-up, that sorta indicates that the low-speed system is working.
That leaves just three possibilities maybe 4.
#1) would be the accelerator pumpshot
#2) would be too much idle timing, which puts the throttle blade too far down the transfer slot. It dries up, and then takes a MS to get started again.
#3) would be really old gas; fresh gas is clear to slightly yellow
#4) would be, lessee, oh yeah, I remember; a defective carb-heat system. That is the exhaust passage under the carb, the heat-riser valve, or the mixing valve in the air-cleaner, if your carb was calibrated for it.
Happy hunting.

BTW yes, that choke mech is designed to come off somewhere in the first three minutes, at freezing temps.
Also; in Ks you shouldn't be having this problem, but; at certain times of
the year, with high humidity, Carb-icing can cause that. Thois is usually a result of a throttle-valve that is too far closed, and lack off carburetor heats. When the conditions are right, ice will form on the outer perimeter of the throttle plate. This will restrict the airflow enough at idle that the engine will stall. This will not be related to throttle changes, it will just stall, apparently for no reason.
I just thought it was worth mentioning.

 

[Loggato]

At 70*F that spring should unwind PDQ, in fact it should be almost limp.
If the engine idles ok after warm-up, that sorta indicates that the low-speed system is working.
That leaves just three possibilities maybe 4.
#1) would be the accelerator pumpshot
#2) would be too much idle timing, which puts the throttle blade too far down the transfer slot. It dries up, and then takes a MS to get started again.
#3) would be really old gas; fresh gas is clear to slightly yellow
#4) would be, lessee, oh yeah, I remember; a defective carb-heat system. That is the exhaust passage under the carb, the heat-riser valve, or the mixing valve in the air-cleaner, if your carb was calibrated for it.
Happy hunting.

BTW yes, that choke mech is designed to come off somewhere in the first three minutes, at freezing temps.
Also; in Ks you shouldn't be having this problem, but; at certain times of
the year, with high humidity, Carb-icing can cause that. Thois is usually a result of a throttle-valve that is too far closed, and lack off carburetor heats. When the conditions are right, ice will form on the outer perimeter of the throttle plate. This will restrict the airflow enough at idle that the engine will stall. This will not be related to throttle changes, it will just stall, apparently for no reason.
I just thought it was worth mentioning.

Accelerator pump works, I can see it squirt when I give it throttle. Number 2 I have no idea.. has fresh gas in it! (I drive the car a few times a week)

but #4 could be part of the problem. I know the valve in the exhaust passage is completely frozen about half open and I have been trying to find a flexi-tube for the passage under the air cleaner.

 

[AJ/FormS]

as to the accelerator pump;
not only must it squirt as opposed to dribble, it must begin to do so immediately when it is tickled. If it hesitates, so will the engine.
A cold engine will not burn dribbling fuel. The droplets are too big and will not vaporize on the way down the cold intake runners. Rather, that fuel will stick to the runners and never get there in time, just as the raindrops stick to your side-windows at 60 mph, and slowly slide down and rearwards. AS the runners warm up, that river of gas will tear off the manifold and enter the chamber, some of it adding to what came in in the usual way, and now she's horrible rich. And some of it will pass straight out the tailpipes unburned.
Stale gas will only exacerbate this. The fuel of today, in a vented container,like your fueltank, will begin to lose it's potency in just a week. The lightest components evaporate at temps below 95*F. These light components are what lights the heavier ones. Without them, you get driveability issues like....hesitations, stumbles, bogs, and stalling. Low compression just makes it worse. The heaviest components might take over 400*F to flame up.

Fuel color is a key to telling how old the gas is and it's associated potency. Fresh is clear. slightly yellow is still ok, but full yellow is making trouble. Red is garbage, it won't hardly light laying on your concrete garage floor. Orange is between garbage and trouble. It will light with an open flame but will smoke and stutter on the floor.

The heat passage under your carb is there to evaporate the puddling fuel and to warm up your intake runners. Evaporation takes heat. So the gas while evaporating, is sucking the heat up like a sponge.
If the heat-riser is frozen open, this defeats the whole system, but now the problem is compounded by the evaporating fuel.
Not sure about a 70Duster, but the later ones had their
intake air temp regulated to be at about 85*F, by the little sampling device mounted on the floor of the air cleaner housing. The carb is calibrated for that temp.
At WOT, the snorkle-mounted Thermac valve opens to allow fresh cold air in. The Thermac valve mixes cold air with the heated air available thru the heat-stove. This is to prevent cold-running problems; once the intake air is over 85*F, the system returns to normal.

So to recap; most of your cold-start systems are not working, hence the problems you are experiencing.

Another thing worth mentioning is your ignition advance mechanisms. Cold-starts need them to be working. Frozen flyweights, broken springs and a ruptured diaphragm will all cause troubles for you. And so will too-wide plug gaps with a weak coil. And a too-low fuel level makes pull-over difficult, also causing a hesitation.