Holley Carb Issues - Bad Float?

[TexasStroker]

This is a 650 Holley on the 408 in my Duster...I always try to progress with carbs and every time it seems fairly simple and then I run into issues that prove otherwise.  I am guessing it is a float at this point, but I would like the insights of anyone more knowledgeable in the field to either confirm the suspicion, or crank out something I'm overlooking.

One day the car had trouble...I crank the key, it fires up, stumbles, and dies.  Ran the issue by the machine shop who also built the carb and he said it sounded like it was probably just the needle and seat.
I replaced the needle and seat, matched the visible threads, had it clocked the same and I get the same issue.  If I feather the throttle I can keep it running with light revs, but once you let off it will stumble and die.

I can open the sight plug and fuel will come out.  Rock the car side to side and you get a few short lived gushes.  So, it would seem the fuel level is too high, right?

I empty the bowl by taking the bottom fuel bowl screw out...works great and I can catch almost everything in the cap of the carb cleaner.  So, the bowl is clear and I adjust the level to prevent the issue.

As per Holley I started by turning the nut about 3/4 of a turn clockwise.  Cranking the car only (mechanical pump), it catches, fires, runs, and then dies.  By the 3rd crank you just kind of assume it isn't going to happen and check the fuel level again.  Open the sight plug and it flows about like last time.  Rock it and the surge of fuel looks the same.  Pull the fuel bowl screw and the cap fills up pretty much the same.  So, I empty the bowl and repeat, turning the needle and seat half a turn in to lower the fuel level.  Crank, fire, stumble, die...check everything and it is constantly the same.  I never got the fuel to NOT flow out of the sight plug and the cap from the fuel bowl never had a noticeable change in volume.

At this point I figured why not pull the bowl, clean everything, and check for any obvious issues.  I saw nothing.  It is a brass float..it goes up and down.  I thought maybe there was a rouge micron of dirt screwing with the needle and re-tried everything.  Same result.

Is this a bad float?  There was no sloshing inside of it and no obvious, visible imperfections.  For the $12 or so, it seems easier to just bring a new one in than dunk it in hot water.

From what I understand the process has been solid given that I've drained the fuel from the bowl before making adjustments to lower the fuel level...it just doesn't make sense to make the adjustments and see fuel at the same spot with the same volume.

I can either order in parts (float, another needle and seat etc.), or try any other suggestions.  I've diagnosed it as best  I know how up to this point.  I can find a few similar threads across the web and people either never follow up with a solution, fixed it with a new needle & seat, or simply got a new carb.  I re-examined the new needle and seat, particularly the O-Ring and it looks as good as it did new in the packaging.

Thanks for any insights...I'm looking forward to getting the car running/driving again in part so I can move it out for re-wiring the Charger!

[BLK 68 R/T]

Have you tried turning the idle speed screw in at all? is it all the way backed out and not making contact with the throttle plate to hold it open a little bit?

[TexasStroker]

Have you tried turning the idle speed screw in at all? is it all the way backed out and not making contact with the throttle plate to hold it open a little bit?

Have not touched the idle speed screw...when I feather the throttle to keep it going it runs/idles/sounds like it always has.  I can check tonight for contact.

[BSB67]

Is fuel coming out the main circuit at idle?  Did you simply adjust the float when the bowl was off?  Very easy to see what you are doing that way.

If there was fuel in the float, I think you might have noticed when the bowl was off.

[TexasStroker]

Got off work and can confirm that the idle screw is making contact...haven't adjusted it any.

Is fuel coming out the main circuit at idle?  Did you simply adjust the float when the bowl was off?  Very easy to see what you are doing that way.

If there was fuel in the float, I think you might have noticed when the bowl was off.

Funny you would mention adjusting the float with the bowl off...I didn't know of that trick until late last night...I will try it out.  If I remember correctly the post I read said to turn it upside down and turn the needle in until you could see the float's hanger screws.  I also read somewhere about fitting a 1/2" drill bit between the float and bowl...I'm guessing the two are relatively close.

I can only get the car to stay running by feathering it when I'm cranking it...I'd have to try to hit the relay or make a remote switch to monitor things from under the hood.  I saw nothing visibly wrong with the float and there was no fuel in it.

I drained both the front and rear bowls tonight before trying anything and met the same fate.  I checked the oil after my three attempts and could both smell the gas and tell it was thinned out...noticeable degradation since Friday night.  I will be changing it next chance I get to work on the car and may shoot a little in the cylinders to play it safe.

I'm tempted to just pull the carb and soak it with cleaner while waiting for parts to show up.