Re: clogged idle air bleed
[Re: dusturbd340W5]
#510124
10/31/09 11:25 AM
10/31/09 11:25 AM
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Joined: Jan 2005
Posts: 3,638 Oakland, MI
dizuster
master
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master
Joined: Jan 2005
Posts: 3,638
Oakland, MI
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Ray go make another test movie and tap the pump shot. have sombody look at the exhaust for smoke. and clean your garage while your at it.
but you are still dealing with 2 different circuits idle circuit tells you nothing about how it will affect the High circuit when the carb is wide open.
I'm not suggesting to rev the throttle. Just tap the accel pump to squirt some fuel. (no different then just using a squirt bottle.)
If it saves the motor from stalling, the extra fuel is what saved it (meaning it was lean)...
It's still on the idle circuit, just adding some fuel to see if it's lean/rich.
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Re: clogged idle air bleed
[Re: dizuster]
#510125
10/31/09 02:53 PM
10/31/09 02:53 PM
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Joined: Jan 2003
Posts: 8,187 Detroit, MI
CokeBottleKid
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master
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Posts: 8,187
Detroit, MI
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Was the video posted to show that when you cover the idle air bleeds the motor dies?
If so what did that proove? Did the motor die because it was lean, or because it was rich?
If you really want to know, cover the idle air bleeds. When it starts to die, tap on the accelerator pump (squirting a little fuel). If the extra fuel saves it from stalling, that means it's lean. If the extra fuel from tapping on the accel. pump doesn't do anything, it's alredy rich.
This is how I fine tune idle air mixture adjustment too. RPM goes up with a tap, turn the screw out. RPM goes down with a tap, turn the screw in.
The idle air bleed is there to "lean out" the idle main well on the way to the idle mixture screw. By having a "leak" in the "straw" (idle main well) it's pulling on, it mixes air in with the fuel going to the idle air mixture screw adjustment. The reason that it needs this is because the quantiy of fuel needed to idle is very small. It would be very difficult if not impossible to regulate 100% fuel with the screw adjustment. By adding in a significant quantity of air, the mixture screw adjustment is a lot more forgiving.
To clarify... I'm using arbitrary numbers here just for example sake. Lets say the motor takes 1 gallon of fuel per hour to idle. (or 1gph)
Lets say 1 turn of the idle screw will flow 10gph of fuel.
With 100% fuel (no idle air bleed) being delivered to the idle screw adjustment, you can see right away, that if 1 turn of screw can turn 10 times more fuel then is needed, then you'd be trying to adjust the screw by 1/10th of a turn to get it right! Much to fine of an adjustment...
Now take the case where you have an idle air bleed. Lets say the idle air bleed hole is big enough that most of the work being done by the vacuum is sucking air, and very little fuel. (lets say 90% air, 10% fuel).
Now you can see I still need 1gph of fuel to make it idle. One turn of screw can still flow 10gph of mixture. However now since the mixture being delivered to the back of the idle adjustment screw is so lean (remember only 10% fuel now), it takes much more of a screw turn to get that quantity of fuel in the engine. In this case, since you can flow 10gph with one full screw turn x 10% mixture, you end up with 1gph fuel in the engine. By doing it this way, the mixture screw can be much more finely adjusted.
Hope that makes sense!
LOL... by the way, the motor is rich. Try turning the idle mixture screws almost 100% in, and I bet it idles better...
my new best friend
We appreciate the real world testing six but it's a good thing holley doesn't engineer carbs this way "hmm you plugged up that port there so that means less fuel... so make dat bigger"
I will admit it's been a while since I've followed the idle fuel and air bleed ports in a holley metering block/main block but if it's anything like the diagrams posted it's clear if you block the idle port you'll have a natural pressure difference from the fuel bowl to the lower idle outlet.
ToddP also makes a good point that the restrictor sizes relative to eachother (air bleed and idle feed) are quite large and that a good amount of air could be supplied by the bleeds themselves. So not only are you supplying more fuel you're blocking off a possible sizeable amount of airflow.
In either case it's too much fuel, and like dizuster says tapping the accel pump is a good way to find out which.
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Re: clogged idle air bleed
[Re: Quicktree]
#510127
10/31/09 07:03 PM
10/31/09 07:03 PM
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Joined: Jan 2003
Posts: 1,030 JAX FLA
Curt
super stock
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super stock
Joined: Jan 2003
Posts: 1,030
JAX FLA
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Chiming in... a stopped up idle bleed will definately make the idle circuit rich. If the bleed is 100% stopped up it probably siphon the entire bowl empty after you shut it off. The same will happen with the main bleed except you will see the discharge port dripping after shut off untill the bowl is empty. Got to go to a Movie now Curt
Oh yeah...THAT'S gonna leave a mark!
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Re: clogged idle air bleed
[Re: Curt]
#510129
11/05/09 10:35 PM
11/05/09 10:35 PM
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Joined: Jan 2003
Posts: 32,394
Quicktree
OP
I Win
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OP
I Win
Joined: Jan 2003
Posts: 32,394
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Quote:
Chiming in... a stopped up idle bleed will definately make the idle circuit rich. If the bleed is 100% stopped up it probably siphon the entire bowl empty after you shut it off. The same will happen with the main bleed except you will see the discharge port dripping after shut off untill the bowl is empty. Got to go to a Movie now Curt
you were right Curt
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Re: clogged idle air bleed
[Re: Quicktree]
#510130
11/05/09 11:54 PM
11/05/09 11:54 PM
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Joined: Jun 2003
Posts: 9,225 Charleston
sixpackgut
Drag Week Mod Champion
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Drag Week Mod Champion
Joined: Jun 2003
Posts: 9,225
Charleston
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not the first time i've been wrong cbk
Gen 3 power 6.22@110, 9.85@135 Follow @g3hemiswap on instagram
performance only racing, CRT, ultimate converter, superior design concepts, ThumperCarbs
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Re: clogged idle air bleed
[Re: Quicktree]
#510131
11/06/09 12:39 AM
11/06/09 12:39 AM
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Joined: Jan 2003
Posts: 6,591 Canton, Ohio
Sport440
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master
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Posts: 6,591
Canton, Ohio
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Quote:
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Chiming in... a stopped up idle bleed will definately make the idle circuit rich. If the bleed is 100% stopped up it probably siphon the entire bowl empty after you shut it off. The same will happen with the main bleed except you will see the discharge port dripping after shut off untill the bowl is empty. Got to go to a Movie now Curt
you were right Curt
Yep, that seals the deal, the word siphon. The bleeds not only help to tune the circut and add air to atomize with the fuel. The bleeds are essential to shut the flow of the circut off after engine shut down. Via the Siphon effect, the bleeds are a multi purpose componet.
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