I have a pro systems 1000cfm 4150 carb basically is a worked holley hp style carb. The motor is a small block mopar 408 stroker, big solid roller camshaft with Indy 360-1 cnc heads and runs on pump gas. The truck doesn't want to idle on first fire up when engine cold. I have to keep it running with my foot for about the first minute of run time. Then it will idle but kinda low till it warms up then the idle rpm is about 1,100 in park. It is really fat at idle also. I don't remember what size my air bleeds are and will get that info when I get home. I do know the idle mixture screws are at 1 1/2 turns out. The cruise throttle and WOT are perfect and no issues there. I also know it ran best with a 6.5 power valve, had a 4.5 in it and it didn't like it. Rear power valve is blocked and jett spread is 84 front 94 rear. I just went through and cleaned the carb month ago before I put the motor together and have since blown out the air bleeds again to make sure they weren't plugged. I have always had this issue with this carb even with my old set-up with ported eddy heads and a .630" lift solid roller. I haven't put a wideband on it yet but I will be shortly and I also run #8 ngk race plugs as this is a nitrous motor.

what is the timing set at?

36*, also did it on old set-up at 38* I'm thinking one issue is I need to have it idle at 1,200-1,300 due to lack of low speed signal with the bigger venturi size.

i have 1 of those carbs on my 440 . Yep 2 half pumps and will normally fire up dead cold - but will have to hold idle to 900/1000 for about a minute , then will idle roughly till about 130deg eng temp .Will occasionally stall when air is cold when I have backed out of garage and then let idle .By the way mine idles around 900/950 in neutral
great carb though

Tex

Mine is JUST LIKE THIS! LOL! but I agree I dropped three tetnhs on my old set-up when I went from a 950 ultra hp to this pro systems 1000 carb doing nothing else.I do really like this carb and if i can figure out this idle issue it will be that much sweeter

Couple of things. I have one of those carbs, but its on a bigger engine, so you will have to bare with me.

Assuming you checked for vacuum leaks, and you obviously know your total timing, what is your idle timing at? Higher idle timing will drastically improve signal to the carb. I recommend 22-23° at idle if you can dial that in.

Two, #69 idle air bleeds and one turn out on the idle screws will get you more fuel. I run either #69 or #70 on all my Mopars....They like fuel at idle. Stock is #76....Too lean.

PS...That is the best performing carb I have ever had once I thru out all the jetting it came with and started over. I also went with out any power valves and square 94 jetting and got my idle better by 200rpm.....They say that means I have a vacuum leak, but I looked many times and could not find one. The car has gone 6.13 in the 1/8th geared for the 1/4 so far. I went with #28 HS bleeds from the #34's that it came with as well, but my engine is bigger...

Two people have made me multiple offers on that carb....Kinda weird cause I really don't want to sell it I picked up almost a full 1/10 in just the 60ft from a 1.40 to a 1.326 with mine.....deadly consistent.

Timing is locked out at 36*, I have checked for vacuum leaks and have none, I also have new carb gaskets and new nitrous plate and solenoids(Indutction Solutions sledgehammer plate) that were all sealed with liquid teflon sealer. I will check what my air bleeds are and let you know but I might try your suggestions after I get my wideband gauge on it.

The key thing on Holley type carbs is that the throttle blades need to be set at idle so that only a small portion of the transition slot is showing. Do not move the throttle blades once the position is correct! Changing the idle speed with the idle adjust screw is only okay for very minor adjustments.

If the engine needs more air at idle than it can get with the throttle blades in the correct location then you have to get the air from somewhere else. The newest carbs have idle air bypass the older carbs used holes drilled in the throttle blades.

The new Dominators use air bleeds in the top of the carb body that go directly to the intake manifold so you can change jet size to adjust the idle air bypass.

Never had an issue with my carb from Patrick. Had a 1050 on a 511. The idle was way better and overall performance was extremely better.
One question that I would ask is, was the carb built for you engine to start with?
Give Patrick a call his customer service is great. I would definitely buy another carb from him.

Yes ,
mine picked up over a BG825 mighty demon,20+RWHP. But street driving the 825 was nicer when cold , cleared the cold stumble off idle earlier .
I have , like you , put it down to big carb/venturi on a single plane intake . Was the same with a M1 and the current Victor .
A friends 440 with a 1050 Dom is similar . You can hear when pulling away cold there is a stumble till it gets a bit more air speed - fine when warm .
Keep with it ,Patrick said to me next carb will be a Dominator

Tex

Yes my carb was built for my old set-up then sent back to him for my new set-up and still does the same thing. Dealing with Patrick has been a pain for me as it is always"send it back to me and I will fix it" well that sucks. I will just try to fix it myself or deal with it till race season is over then i will send it in to him as I'm tired of waiting and paying shipping costs for an issue that has yet to be fixed!

Correction, I went with #27HS bleeds.......and 94 jets in all four corners. Mine also has the 50cc accel pumps on it instead of 30cc pumps...That is why the 60ft improved.

Mine also has dual 50cc pumps on it, I'm really thinking about going no power valve in front and square 94 jets on mine aswell.

thats what I would do, and check the transition slots like mentioned above

what should they be at? .040" exposed?

Doesn't say much for the company you got it from, if it was supposed to have been tuned for your car when you got it.

I start with about .020 .030 or square and go from there. If that has the 5 e holes with one plugged it's already jacked there plus the 45 squirters and on and on. Good carbs with the wrong peeps tunin em.

I agree, i also open the rear blades a little if I need more.

That can work but can also make idle and cruise rich.

I'm watching this thread, because I have the same thing going on with mine. I don't mess with it much but at some point I would like it to idle clean when good and warm