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Ted
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Half-dude (9/21/2016) Is there a way to visually check if that's whats happening? Like can I see a flow of fuel from the power valve through the choke plates or anywhere else?No. You can’t see the extra fuel visibly. Even if you could look into the primary side of a Teapot when it was running, the enrichment circuit doesn’t dribble or pour the extra fuel into the carb. It is metered in as atomized fuel through the main power circuit. If you have a wide band oxygen sensor hooked up to the car, then you should be able to detect the richer fuel mixture as it’s going out the exhaust when the power valve is open. The power valve enrichment holes themselves are quite small and affect the idle mixture only slightly. Those particular holes supplement the main fuel circuit which comes into play only when there’s enough air flow through the venturies in which to activate that particular circuit. That circuit using that diaphragm in which to work the power valve is very touchy in getting the diaphragm perfectly sealed to the cover so that the manifold vacuum keeps the diaphragm in a ‘pulled up’ position in normal circumstances. The power valve is normally open when the engine is not running and as soon as it starts, the power valve closes as soon as there is sufficient manifold vacuum to do so. As the diaphragms get some age on them, the rubber gets stiff making it more difficult for them to pull up and consequently allow the power valve to close. I’m surprised Holley used that design as long as they did as it was problematic in getting to work as designed.
Lorena, Texas (South of Waco)
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Kahuna
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I don't think you'll have much success looking down a Teapot carb. It's very difficult to see anything
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Half-dude
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Is there a way to visually check if that's whats happening? Like can I see a flow of fuel from the power valve through the choke plates or anywhere else?
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Ted
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Half-dude (9/20/2016)
....If the power valve is always open shouldn't i be able to see fuel coming out the secondaries? The power valve (enrichment circuit) is for the primary side of the carburetor and simply allows the primary fuel mixture to fatten up as the manifold vacuum drops to a given point. The secondary side jetting is controlled completely by the secondary jets and has nothing to do with the power valve circuit.
Lorena, Texas (South of Waco)
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Half-dude
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I had a leaking secondary problem with the carb before I had it rebuilt one of the secondaries was always running.
If the power valve is always open shouldn't i be able to see fuel coming out the secondaries?
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Kahuna
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You definitly have a carb problem of some sort. On the Holley 4000 carbs, the power/economizer valve is held closed by spring tension on the valve itself. The valve is opened when vacuum is decreased to a small diaphram with a pin located directly above the power valve. If that part is installed incorrectly or the diaphram is leaking, the power valve will be open all the time. A mentioned earlier, closing the idle adjustment screws should stall the engine. Either Mike Suter or Sal Scicala can fix that carb for you. I have no info about the Carb & More that did the work on your carb
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chris70
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Make your readings in P/N the drop in rpm and vacuum in gear is normal.Mine goes from 16/17 in Park and 9/10 in Drive.You must achieve the highest vacuum by the lower rpm for a correct carburetion.
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Half-dude
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charliemccraney (9/19/2016)
On modern carbs, the engine should die if even one screw is completely closed. If it doesn't die, it's most likely that the power valve is blown. Another possibility is that the throttle blades are open too far and it is actually idling on the primary circuit. Unless you have a radical cam, the throttle position is probably ok. I don't know how much of this translates to a Holley 4000. Thanks, it sounds like it's time to email Carburetors and More and see if they made any substantial modifications to the thing when they rebuilt it that would explain that.
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Half-dude
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chris70 (9/19/2016)
Hi,here is an interesting article that can help you with the vacuum gauge: http://www.secondchancegarage.com/public/186.cfm. It seems to me that your initial reading was very good 22hg is fine,in the last video the vacuum is way to low.If the engine doesn't die with screws all turned in there is something wrong with carb.It's getting fuel somewehre it shouldn't. Thanks for the link! I'll be sure to check it out. As for your comments I just wanted to point out that between those two videos, the one with the good reading was with the engine in Neutral or Park. The other was with it in Drive with the Parking break on. I'm not really sure what gear it should be in when you do a reading and if it should make a difference. I don't know why but my car has always been like that, it idles too fast when out of gear, and drops a lot when in gear.
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charliemccraney
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On modern carbs, the engine should die if even one screw is completely closed. If it doesn't die, it's most likely that the power valve is blown. Another possibility is that the throttle blades are open too far and it is actually idling on the primary circuit. Unless you have a radical cam, the throttle position is probably ok. I don't know how much of this translates to a Holley 4000.
Lawrenceville, GA
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