Your OP didn't open up with any *reason* that your carb had failed.

If you had offered only the *symptoms*; really rich and dying at idle, I would have suggested a stuck egr or sloppy timing chain.

If the symptoms suddenly appeared I'd say egr.
If it's been getting worse over time I'd say timing chain.

 

If you haven't drop the float level until you get it to idle then try bringing it up to bottom of port where it should be.

 

Just found this info on plugging the Power Valve

 

You would expect that a carburetor would need an enrichment circuit to operate properly under varying load and rpm's.

4180's are jetted about as lean as they could be to still function in a street vehicle.
Annular boosters and EGR help fuel mileage quite a bit.

 

If you get everything tuned up correctly, why would you need to plug up the power valve? I think you're barking up the wrong tree, so to speak.

 

Okay I'm back focusing on this powervalve situation.

It is possible I used the wrong gasket. I used a solid round one with a round hole in the middle, rather than the one with a 3 spoke hole in the center. So I will change that out today.

From the photos I posted above (of both my old one and the new one that came with the rebuild kit), can you tell if either of these is 2 stage or 1 stage??

Can you point me to that addendum where Holley explains it is no longer producing 2 stage power valves??

Interesting that many sources refer to this item as a 'power valve', and yet it appears to function as an 'economizer valve' both in other forum discussions and on the parts list quote in my rebuild kit ?

 

Both are correct. Engine vacuum keeps it closed, at idle or cruising steady. Stomp on accelerator - vacuum goes away, valve opens and more fuel is provided.

But some engines don't have much vacuum, or it isn't steady - high performance. If the wrong size valve is installed in an engine too; it will never close, and run terrible.

 

Just saw this explanation on another forum:
So I do not see where the EGR system helps with fuel economy? I do see where it is an emissions tool.

I believe much of my EGR system has been disabled by the previous owner. I will check for possible vacuum leaks, but I have not disturbed this 'system' of mine during my recent carb rebuild task, so I fail to see why this would give me problems now, when it did not before?

 

Interesting.
Is it possible to tell if a power valve is operating properly by trying to blow or suck on both ends of the valve? I tried that on my old valve and found that I could not get any air thru it if I blew on either end.
But if I sucked on either end I could get air. ??

 

This page depicts a number of photos of 4180 carbs as used on Mustangs:
How To Understand The Holley 4180 - Mustang Monthly
But the power valve photos (2) shown seem to depict a valve similar to the one in my rebuilt kit, RATHER than the one I pulled out of my carb before rebuild?

 

Here is a photo of a powervalve that looks to be identical to the one I pulled out of my old carb:
Motorcraft 2100 & 2150 2 Stage Power Valve | 2 Barrel Carburetor

It refers to it as a 2 stage powervalve.
Notice it did NOT address the question of changing from a 2-stage unit to a 1-stage unit.
And it just may be possible that I got a 1-stage powervalve in my rebuild kit??

 

You're fixated on the power valve as the sole cause of the problem when it could very well be secondary result of other problem instead.

Singe or dual stage valve either one if "new" wouldn't cause a overly rich idle condition provided everything else is as it should be.

If another issue is causing very low engine vacuum, two main contributors already brought up, base ignition/valve timing way off and or EGR system leaking allowing large vac leak either one or any combination of the two could cause the power valve to open when it should be closed.

Google search brings up reason why Holley discontinued the 2 stage PV.

http://static.speedwaymotors.com/pdf...itaddendum.pdf

http://documents.holley.com/199r7903-2rev1.pdf

You first stated,

Long story shortened, I was experiencing some flooding of the carb that I determined was due to faulty o-rings on the float valves.

and then later in the thread,

I can't even get it to idle so I can measure any RPM or vacuum. It just stalls out from too much fuel

Following along from the very beginning long before posting for the first time I assumed it ran, ran a tad rich heck extremely rich even but that it did run maintaining some semblance of an idle for ya, I believe both posters before me from reading their posts/comments made made that assumption also but may be wrong.

Your later statement about how it won't even stay running long enough to check timing or get a vac reading suggest it has bigger issues other than carburetion.

Might be a good idea to look to those other issues making sure they are not a problem creating a carburetion issue due to "cause and effect" rather than the sole source of its issues.

Rebuild kits almost always contain several gaskets for the same location as they cover multiple carbs, if you didn't you should have matched up each gasket that had been removed with one from the kit.

http://documents.holley.com/199r10060rev.pdf

 

You're correct Dan, I may be fixated on the powervalve too much. Its just I had it running pretty decent before this sudden 'excessive rich idle', and I was narrowing it down to carb problems only.

It also appears as though i am not the only person to experience problems with these 'powervalves'

So I'm headed out the door to get a new vacuum gauge (misplaced mine), and I'm going to look at ignition timing also.

Meantime I do hope to find out if the powervalve I got in my rebuild kit is even close to what I need,...and that it is not leaking upon setting as one report had it.

 

EGR allows the engine to run extremely 'lean' mixtures and large amounts of ignition advance under light load (cruise) conditions.
The carb can be jetted lean 17-19:1 and run 50 degrees or more of ignition advance without detonation because oxygen is being displaced from the intake charge when the EGR valve is open.
The engine doesn't knock or overheat because a lack of oxygen slows the burn rate and effectively 'richens' the mixture.
This helps NOx emissions by keeping combustion chamber temperatures below the threshold for these elements to combine.

When the EGR fails by rotting through or sticking open, there is not enough oxygen available at idle (throttle plates closed) to support combustion.
The engine stumbles and dies because the fuel won't burn (too rich)
A manifold vacuum leak would actually help... in this situation.

As for Holley's explanation about single stage power valves (since you didn't buy the proper Holley kit) look at the tech documentation links on the product page of their website https://www.holley.com/products/fuel...s/parts/3-1346
I have no good way -on my phone- to cut and paste the body of the linked pdf into my reply.

It's an 'economizer' valve when the manufacturer wants you to think starving an engine for fuel except under load is a good thing.
It's a 'power valve' in the performance aftermarket when Holley wants you to see it as a feature.