Rich at idle! Help!

I have a 440 in my ramcharger with a 4150/1050 proform. No matter what I do it runs rich at idle.
I set the throttle blades to show the transfer slots just as I should, set the idle mixture screws 1.5 turns.
Checked the power valve, opened up the idle bleeds from 73 to 76.
It has around 8” vacuum currently. It has 10” if I turn the idle up a little.
But no matter what I do it has little to no effect on a/f ratio of 10.8-11.2.
I’m at a loss.
It cruises around 12.5 and is around 12.5 at full throttle.

If the idle screws don't make much difference then you need to reduce the size of the idle restriction in the metering block. Depending on which carb you have the IFR might be a drilled hole or it might be a jet.

after shut down for 5 or 10 minutes,does it restart with long crank or blubber- it could be a internal leak like a power valve

No matter what you do??

Can you stall the motor by turning the mixture screws all the way in?

If so, I’d say the circuits are functioning properly...... and probably need a different calibration.

If it won’t shut off by turning the screws all the way in....... then figure out where it’s getting fuel from when the screws are all the way in.

It does die if I turn the mixture screws too far. But to the point it doesn’t like it, doesn’t change the a/f much at all.
When I took the idle bleeds out of the primary completely it went to 12.2 but then the accelerator pump didn’t work the way it should. I put a 4.5 pv just now and it made no difference.

It starts and drives no problem at all even after sitting. And it does run just fine. I just can’t get the idle to stop running rich.

It does have jets inside on the metering block on both sides of the power valve, along with holes that appear to be for jets. I bought the carburetor new so those are whatever came on the carb. And I don’t know what those do.

For what it is worth it didn’t seem the idle mixture screws made any difference for vacuum either. When I opened them past 1.5 the vacuum didn’t go up.

Ok now that I have made other adjustments I’m not sure what caused this but now the screws are leaning the mixture. What is the most you want to turn these in? I’m at 12.2 now and the screws are about one full turn out. But now it stumbles really bad when I try to take off.

Lean it down a 1/4 turn and open the blade to get the rpm back

The carb should idle on the idle circuits, if it is 4 corner idle adjust both throttle shafts, so the throttle plate DO NOT expose the transfer slots If they are exposed at all it is not idling on the idle circuits only like it should
Years ago some one on here started the misinformation about exposing the transfer slots to make THEIR carb idle instead of fixing their real issues with that carb

I’ll give that a try next but now it’ll have to wait until tomorrow.

Those are probably the emulsion jets. The idle feed restrictions will be in the upper corners. Maybe post a picture of your metering block and someone will show you what is what.

Smaller IFR or larger IAB would be a start.

Try dropping the float level slightly. That will help sometimes to clean up idle.

You should have more control over the idle setting, my guess is a smaller IFR so the mixture screw is less sensitive to movement, requires more movement to alter A/F ratio.

Make sure you have initial timing in the correct spot too.

Yes, timing with a big cam should be at least 20 or 25 degrees. Smaller IFRs usually solve the idle tuning problem but sometimes it just takes a little more timing.

Cam is only 230@050 and 112lsa. 050. 9.8 compression rpm intake. Motor made 490hp/553tq.
I did open up the idle air bleeds to 76 from 73. It’s more responsive to adjusting the idle screws.
I got it to 12.2 by closing them up to 3/4 or 1 turn out I can’t remeber exactly. But now it stumbles and dies when I try to take off.
Next idle try to open up the butterflies some to see if it helps, but doesn’t that uncover too much of the slot?
Timing is 18initial 36 total.

Maybe re calibrate your Gauge

I believe the gauge is pretty accurate, being what I saw on the dyno through the rpm range
Was consistent with that I seen on this gauge when I put it in the truck.
FWIW the idle wasn’t this rich when I first installed the engine. Which leads me to believe it is something I am doing wrong.
I installed this on my cuda and had to make adjustments then put it back on the truck.
It doesn’t seem to run rich at idle on that motor which is a 410” with big Indy single plane and much bigger cam.

It sounds like one(or more) of the bleed are plugged with trash or something

Check your exhaust system for air leaks, they will really mislead the O2 sensor and gauge

P.Body I think that was a possibility. Because once I drilled them out just a tad bigger,
my idle screws started to finally have a bearing on A/F. Once I get another chance I’m going to lean it out just a little more and then set the idle a little higher and see if the problem is soloved. Hopefully that gets rid of the off idle stumble. I’ll keep the post informed of my finding. It could be a few days before I get back to it.

18 Initial is not enough. You can lean the idle circuit and turn the mixture screws all the way in, but unless you start to burn that mixture at the proper time you will get incomplete combustion of the fuel. Your idle vacuum is low, with low idle vacuum the fuel takes longer to burn because it doesn't vaporize as much of the fuel. For testing purposes lock out your timing to 36 degrees, see how it responds...

My Pro Systems 950 was dead nuts on going down the track but pig rich at idle, adjusting the idle screws didn't do anything, I sent it Thumpercarb, he only worked on the idle circuit...It's perfect now. 1/8 turn on the idle screws makes a diff now where before NOTHING did.

My feeling is that the carb base calibration isn’t set up for only 440” and a small cam(230@.050).

I’d guess the idle circuit was calibrated to be used on a motor combo that’s quite a bit “racier” than that.
In a nutshell....... it’s the wrong carb.

As an experiment, I’d see how it would work if it were functioning more like a carb with a 2-circuit idle.

First, I’d look under the carb at the rear throttle bores.
I’ve seen some of them have the tiny idle discharge ports under the transfer slots, in addition to the discharge ports fed by the mixture screws.
If it does have the extra tiny holes, try turning the rear mixture screws all the way in, and basically close the rear blades.
You’d also swap the rear idle air bleeds to something much smaller, like what you’d use for a hsab.
Again, this is only if the tiny discharge holes below the transfer slots are there.

If they aren’t there, then I’d run the rear mixture screws not quite all the way in.
Maybe leave them out about 1/8 turn.
I’d still run the rear blades at almost shut(to start).
Leave the air bleeds alone.

Now, almost all of the idle fuel will be supplied by the primary side, which should noticeably improve the mixture screw sensitivity on primary side.

Start with the rear blades basically closed, primary blades set to as far open as possible, based on the transfer slot exposure.

After getting the motor up to full temp...... then you can tweak the rear blades open more to adjust the idle speed higher if necessary.
Don’t adjust anything until you’re at full operating temp.

I’ve found that 2 corner idle carbs can still work very satisfactorily with the mixture screws out as far as 3 turns.
The range I like to see then in is 1-3 turns.

If you can’t achieve a satisfactory idle mixture by 3 turns, then add 1/16-1/8 turn at a time to the rear screws.

Having the rear transfer slots not showing(or very minimally showing), along with the mixture screws turned way in will also lean out the part throttle cruise.

Go down .002-.003 on the ifr's and lower em if they're up top where the usually are is shelf carbs.....

Thank you Dom. I will try these things once I get a chance. I haven’t touched the ifr. Maybe I should just go ahead and make my cam change to the 243@050 .600 on 108 now and see what that does. I do plan to replace this carb eventually. I just don’t currently have the funds.

Big is USUALLY better imo and the bigger cam will change the vacuum and characteristics of the car as well.........

Not to hijack but what did he do to it? My P S 950 acted the same way.

Moving them down below the float level made a big difference in reducing fluctuation in my set-up.

You’re not hikacking 👍. I am curious as well. I haven’t had a chance to get back at it as the weather has been rainy and cold and I don’t have a shop. My plan is to work on it more this weekend. From the above posts it appears I have some things I can try.
Pondering over this I’ve been thinking. My vacuum is lower than normal at 7”. It’s usualy around 10”. I plan to plug the back of the carburetor to see if that helps. Right now it goes to the power brake booster. And I’m curious if I could be losing vacuum from there? Or could it be a carb adjustment? It is steadily 7”. I’ve seen as much as 12” on the dyno with the dyno 850 carb.

My normal mods plus compensated for his horrible 6000+ feet of altitude....Fast is right about QF and some other carbs having piss holes below the t-slots on the secondary side so I plug em w/lead shot and start w/the primary and secondary blades showing to same amount of t-slot for starters then salt to taste.....