Engine runs terrible when cold, great when warmed up

Hello, get ready for a strange problem that I am having over here....
My '70 Charger has had this problem for several months but because I've been making all sorts of other changes, I haven't been able to spend time on this one very annoying problem.
I will list the combination first:
440/493 with Edelbrock heads, EDelbrock RPM intake, MP electronic ignition, Demon 850 vacuum secondary carburetor. NGK spark plugs, MP 528 solid cam, 1.6 rocker arms, 2" TTI headers, 727 trans.

The symptoms: On the first start of any day, weather in the 60s to 80s, the engine is difficult to start and when it does, it runs as if it is only hitting on 3 or 4 cylinders. The Air/Fuel gauge shows it to be running way lean, past the limits of the gauge. It feels like a misfire/misfires.
As the engine warms up, it smooths out and runs like it should.
It is certainly unrelated but this problem happened some time after I started the A/C swap including the new water pump housing, radiator and shroud.

I suspected that the carburetor could be gunked up because in this past year, I've only started it and ran it here and I've only driven it in the back yard here. The 91 octane gas is old but does not smell varnished.
I had the carburetor rebuilt and added a replacement electric choke. The car runs the exact same as before. I cannot find any vacuum leaks anywhere.
When it was acting up before and today, I've tried swapping distributors, electronic ECUs, ballast resistors and coils. I have tried bypassing the ballast resistor by using a jumper wire to connect the wires. Each time I changed something with no improvement, I shut the car down and try something else. Of course, each time I start and run it, the engine gets a little warmer and on the way to running normal again.

So, since none of the parts swapping seems to make a difference, I'm looking at what I have not done.
The gas is old but it does not seem bad.
The plug wires are solid core Taylor and seem to be in good condition.
Battery is new.
Alternator is charging normally.
I am pissed because I can't think of what conditions exist here on a cold start that go away when the engine warms up.
This is a fairly new problem. Since 2008 or so, I have run without a choke and while the engine did run a bit rough when cold, it ran okay to idle on it's own.
I thought adding the choke would richen it up on the cold start but it made zero difference.
The engine side wire harness was new in 2013. The engine is well grounded. Battery is in the trunk.

I plan to put in 5 gallons of fresh gas tomorrow but it will have to mix with what is in there now. There isn't much, maybe 2 gallons.
Any ideas ??

You've added the choke but is it actually closing fully & does it have a pull-off, an unloader & stepped idle?

I was thinking a choke issue myself.....

It is electric, is wired up but the butterfly wasn't closed. I thought maybe because it was almost 70 degrees, the choke didn't close.
It does have a stepped idle. It is essentially a Holley electric choke design.
I know that the choke was a shot in the dark because I'm just "shotgunning" this problem.
It ran decent without a choke for all those years. This is a recent problem and I'm having a hard time figuring out what I may have done to suddenly cause this.

Add more tension to the choke.... Yes, you would think at 70 degrees it should be open, but the lean condition is telling you otherwise.... loosen three screws & make a little adjustment...

When I was trying to start it after installing the carburetor, I could not get spark. The coil had power but the test light was dim.
I should be more skilled at diagnosing these "No Start" problems by now. I usually just replace parts until the car runs. What voltage should the coil have with the engine off but with the key in the ON position?
I have 3 old cars out back that I can test to compare numbers.

1 Wild R/T said:

Add more tension to the choke.... Yes, you would think at 70 degrees it should be open, but the lean condition is telling you otherwise.... loosen three screws & make a little adjustment...

Click to expand...

I will try that but it digs at me....Since it ran okay without a choke before but NOW it runs bad when cold, what could be the root cause? Would a richer mixture maybe only mask an underlying problem?

Is there anything in an ignition system that could operate better when warm than when cold?
Could "seasoned" spark plugs do this? I don't recall how old these plugs are.

That really depends on the ignition system & if the ignition is in a grounding condition or an open condition.... Using a test light with the engine cranking the test light should pulse... If it's a points type ignition & the points are close the light is out... Same thing with electronic but no points so it's hard to have a visual clue.... Points open the light is on but if the key is in the run position the ballast cuts the voltage to around 7-9 volts...

What's your timing set at? Is it locked in?
I know you say after it warms up it runs better, is it hard to start after it's up to temp too?

Yeah, I recall that the voltage is 12 at cranking but lower during run and when running.

Mike67 said:

What's your timing set at? Is it locked in?
I know you say after it warms up it runs better, is it hard to start after it's up to temp too?

Click to expand...

Timing was not changed. 17 initial, 31-32 total with vacuum advance.
Starts easy when warm. Even better with this new battery!

Kern Dog said:

I will try that but it digs at me....Since it ran okay without a choke before but NOW it runs bad when cold, what could be the root cause? Would a richer mixture maybe only mask an underlying problem?

Click to expand...

I really think it's the shitty California fuel... I use to be damn good at tuning carbs, the reason I went to FI on my Challenger is I couldn't get the car to start quick & easy when cold anymore... Five years ago it was fine, four years ago it started getting worse three years ago I threw in the towel....

Kern, go efi if you’ve got the budget for it.

Oh, I have the budget but I figure that if I can't figure out a carburetor setup, I'd be far worse when an EFI problem pops up!

I just went out to check coil voltage.
Ign ON but not running: 7.9.
Engine running: 11.4. Huh? I thought it was supposed to run below 10 volts with the engine running? Also, the numbers jumped around from 4 something to the peak of 11.4, hanging on 11.4 for the most part though.

My 67 Dart had 5.7 volts with Ign ON. The 75 Power Wagon had 6.4. Both start and run fine with no choke in 60 degree weather and above.

Lean air/fuel mixture with the choke on is a clue.
The cold engine requires a rich mixture.

I've said it before but I guess I'll say it again... The fuel has been formulated based on EFI cars, it virtually needs to be kept pressurized to keep it from evaporating.... The problem is even worse here in California where they reformulate constantly for emissions...

I put the EFI on because of the starting issues more than anything but now that I have a system that works pretty well there are other things I appreciate about it....

When I was younger I'd come home from a cruise & pop the hood, pull the carb apart on top of the engine & change jets or squirters & never give it a thought... Now between worrying about the potential for a fire plus just reeking of gasoline I really hate to work on a carb on a hot engine anymore..

So when I'm trying to tune I'l wait till the engines cold, make one or two adjustments & go for a drive.. If it's not right I wait till the next day if I have time to make another adjustment...

With the EFI I grab the hand held programmer & change A/F ratio, Idle speed, accelerator pump, what ever I want... I drive a few miles & tweak a little more, never raising the hood.... Nice...

FBBO member AJ/FormS responded in my other thread about this carburetor:

"ok so the California gas is about a year old? And the starting gets worse every month? heehee.
Pull a fuel sample out of the float bowl; it better be clear with no water in it.
Slightly yellow is a hard start but will run well enough to run around at Part Throttle.
Orange is really hard to light, but if you get her running, you can put her on the trailer.
Red is as good as skunk pee. Pour some on the floor and try to light it; you'll need a torch. Once lit it will smoke and stutter and stall out, leaving an ugly greasy stain on the concrete.
Modern non-ethanol gas, stored in a vented car gas tank, is good for about a month, maybe as much as two, but starting will suffer. Oxygenated is about half that in winter, one week in summer, or less depending on the ambient and if it sees the sun, like in a plastic gas-can..
Color is a pretty good test
Stabilizer will take even alcoholized gas to a year or more, here in Manitoba..

My factory ECUs have always been good down to 9.5v

As the gas ages, the more volatile compounds evaporate leaving the more syrupy, harder to burn compounds behind, which become more and more concentrated over time. To continue burning it, you will need to use more and more of it by increasing the throttle opening....... which drives the AFR ever leaner. A lot of that Orange gas is gonna go straight thru the engine unburned, and stink up your garage. And IDK what your AFR is gonna make of that.

EFI cars have relatively sealed fuel tanks and even a year later still start and run well. Course I guess the computer is probably working overtime....."

Well, the gas is not 100 % clear. It does have a slight yellow tint to it.
Would gasoline of this age allow the car to start and run bad but then allow the engine to run better once it warms up?