I can live with a rough idle when cold, but too rich at idle when warm is an issue I would like to correct. Cruise and WOT on this carbv is awesome though.

Well I put the carb back on and decided I will double check my idle mixture screws. They were at 2 1/4 turn out, so yeah just cause you are sure doesn't mean you are... you know what I mean. So I have them at 1 1/2 turns out and will double check warm idle tomorrow, after some burnouts

don't worry about it, tuned right it's not an issue. ran plenty of non PV carbs on the street. as long as it's not fouling plugs you are good imo.

The idle mixture screws carry out farther in the rpms than most may think and with lowered ifrs they become even more sensative.

I'm 99% certain that if a Pro-Systems carb (with F and R idle screws as I presume most are) is correctly sized and calibrated for a motor combo, you shouldn't need anywhere near 2 1/2 turns out on the Idle screw. Check with PAtrick because mine only needs maybe 3/4-7/8 of a turn from bottomed out. He said if it cranks with 1 full turn its In the right range and turn them In until you get a stumble. They are much more sensitive than an oem calibrated Holley.

Cold start (or Especially if it hasn't been cranked in a while) I'll sometimes fatten it up a 1/8 turn and turn the idle screw a full turn for a few minutes, then I back it back down to normal and I'm good for the rest of the day, as said its a price unwilling to pay for a non choke racey motor combo. Once it's warm its 110%

So we went to opening day at Empire today....Ran my Engine builders 69 Barracuda with the 477 Hemi pump gas street motor. It has a .540 solid lifter cam and a RBRE single plane intake. Your basic 10:1 street hemi with a 4.15 stroke.

We put my 1000cfm 4150 on it and it fired right up....All with the settings above:

94 jets square, no power valves, 45 squirters front and rear, 50cc accel pumps front and rear, #70 air bleeds for idle, #27 hs bleeds....

Only made two passes...

Off the trailer she went 10.57 at 127.3mph....

Next pass 10.52 at 127.8mph with #28 hs bleeds was the only change. All that with a slower 1.48 60ft over the first pass. Track was off a little and we are not sure where to run the tire pressure yet.

Fires up the minute you touch the button, no input from your gas pedal needed, and runs just as awesome as it did on my 512...

Time between trails was really long, plus a swap meet so I only made two passes....And nothing broke.

I have a Prosystems 950 4150 that I bought from John at Induction Solutions, he used to work at Prosystems so he set it up for my 500" low deck street combo. It runs awesome, fires right up in any temperature and drives around town perfectly, I can stab the throttle at any speed or RPM and it's perfect.
With that said, I don't think there's any high performance carbureted combos that will fire up dead cold and idle perfectly, without a choke. I don't have a problem with taking a minute to feather the throttle a little til it's warmed up. If I'm really worried about it I just give the idle screw a half turn clockwise so it idles higher, after a minute or so I turn it back down and go cruisin. On my 69 Dart I rigged up a rod that ran from the idle screw to a knob on my dash, I could adjust the idle while sitting in the car.

I'd have to check my build sheet for the bleed sizes but my jets are 76 front with 6.5 power valve and 86 rear with no power valve.
Back when I raced I ran my carb square jetted with no power valves, always seemed to work a hair better on the track with a slightly better 60 foot.
On the street it was fine but was pretty choppy slowly pulling away from a stop. Sometimes if I was planning alot of weekend cruising I'd throw the power valve back in the front along with smaller jets, about 8 sizes smaller.

Well I ran it today and with the idle screws at 1 1/2turns it won't idle AT ALL! cold, warm, running after 10 minutes, doesn't matter I have to keep feathering the throttle to keep it running. Think I'm gonna try What Dragula said with the #70 air bleeds on the idle circuit and give it another try.

70 Idle bleeds work well in several gas applications.

Here's a pic of my ProSystems 950HP 4150 build sheet.
Idles mixture screws are 1 1/4 turns out, power valve in the front only. I have 2 light weight springs in my distributor, I even stretched them a little so my timing is pretty much locked out, idles around 30 degrees and goes to 34 total when I rev it.
Runs great on the street and idles nice in gear.

UPDATE;

I ended up going to #63 idle air bleeds in the front ans #55 idle air bleeds in the rear and 2 turns out on the idle mixture screws. The truck idles WAY! better now and it isn't rich at idle anymore. Cold start I still have to hold the throttle open some for it to idle but only ofr a minute then it idles fine on it own. I also have the idle at 1,200-1,100 in park or neutral and the timing at 38*.

good result
I did find this thought it may help - even if a little late

Tex

Way too rich...Please square them at #70....from 76 to 55 is a ton and not needed.

You made it more rich if you went from 76's to 63f and 55r rear.

It had #65's in it and I went down to #63's front and #55's rear. It idles the best it ever has and isn't rich at idle anymore as I'm not having to work the throttle to keep it running. Patrick had put #65's in it last time I sent it in for the same complaint. he says because I have such huge heads and carb on such small cubes the velocity at idle is very low. I need the carb though as this is a nitrous motor and runs its best times with this 1000 versus the 950hp i had on it.