Why so rich on first drive of the day?

[Hedley Bean]

Hi all. I'm looking for a better understanding of cold engine operation. On the first cold start-up of the day my engine will barely hold an idle and I have to keep some throttle on for a few minutes until it gets warm (this doesn't bother me--I have no choke/heat crossovers/etc). The wideband will show 16-17 numbers briefly while it wakes up, as I'd expect it to with mostly un-vaporized fuel and air going out the pipes. I'll get it to where it will idle on it's own which takes maybe 2 minutes, then hit the road.
As soon as I start driving it runs very rich, until I shut it off and let it heat soak for a good while; like an hour or more, at which point if I take the car back out it behaves like I expect it to, and the A/F readings fall in line with the performance. I do tune to the hot operating temps, but shouldn't it want to run leaner during that cold first drive, instead of richer? Or do I have it wrong?
My gut tells me to just keep tuning hot, and the cold operation is what it is..but my curious brain wonders why the 'morning blubbers'..and as always there's a very good possibility I'm just plain clueless...

I'm pretty much to the point where I simply ignore those first-drive numbers and the sluggish response, knowing that after some shut down soak it will be fine the rest of the day.
Oh and If it matters, a "cold morning" drive for me right now is maybe 65°-70°F (a summer scorcher for some of you )..but I feel the air temp isn't really the issue as it acts like this even in winter when the max temps may only be in the 50s-60s.


Current combo is as follows. It runs well but feel free to point out anything that seems wonky, I'm here to learn...Thanks

505" RB Mopar in a 3700 lb car w/driver
Old-timey 727/PTC 9.5 converter/3.73 gear/28" tire
10:1 Scr/.039 quench distance
Trick Flow 240 heads with their single-plane intake
250@.050/.572 (after .020 lash) SFT cam
BG Speed Demon 850 Mech. Secondary carb--1.56x1.75/jetted 80/86/9.5PV/.035IFR/.073IAB/.031MAB/all T-slots @ .020"/still fine-tuning
"Idle-eze" bypass air in use
Timing @ 21° intital/35° total/900 rpm neutral/800-850 rpm idle in gear
Ported vacuum advance starts moving at 12-13in/hg with a max add of 12° at full cruise vacuum (20in/hg)
10in/hg at idle--jumps to 12"-14" as the blades crack open--15"-20" at various steady-throttle cruise speeds under 60mph.

[Geoff2]

Needs more idle timing, easily done by switching your vac adv from ported [ useless ] to full manifold vacuum. This will add timing at idle & could need as much as 40* at idle [ yes, 40* at idle!! ]. An adjustable vac adv unit will be reqd to work with the low vacuum. Adding more idle timing increases idle rpm. That will allow the speed screw to be backed out to get the desired idle rpm, reduce the amount of T slot showing, & lean the idle.
If you think 40* at idle is a lot, I had one engine that gave best idle quality/highest rpm'/highest vacuum with 53* timing at idle.....

[F-BIRD'88]

Lock the mechanical adv out
35 deg fixed.. Then as said try full vac on the vac adv and play with rate . Give it what it wants.
A dual plane (can be Mopar dual quad ) will run SOMuch BETTER. There is not a carbed engine made that does not benefit from under carb plenum heat.

A 750 HP carb (820 cfm) will run and drive MUCH Better.
With your short gearing it will ET as good or better.

With the increased base idle timing you can re adjust the idle eze and then RE-TUNE THE primary idle air bleeds.