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gas pouring out of secondary boosters?!?!?
Went to start the car this morning after it sitting for a long while. Cranked it to fill the float bowls, and the car started, but idle was terrible and it was smoky. Turned the car off, pulled the air cleaner, and saw (and heard) fuel pouring out of the secondary boosters. The contents of the secondary bowl emptied into the main body. On the plus side, all that gas dumping through the manifold into the cylinders explains why I get a whiff of gas in the oil
The carb started life as a holley 650 dp, but I replaced the main body with the proform. I'm digging through my "Super Tuning and Modifying Holley Carburetors" book, but can anyone shed light on why this is happening? The primaries were not leaking. Would an old/bad gasket cause this? Thanks, JLW |
Dried up gasket is my guess.
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yep something dried up or stuck.....get a gasket kit and take the secondary side apart......probably can do it on the car...
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I'd say dried up perished fuel line has caused the secondary needle and seat to jam open.
An excessively high float level (or in your case, an uncontrolled float level) is the only way fuel will pour out of the boosters. Pull the bowl off, invert the bowl and blow through the inlet, chances are the needle isn't seating. |
Gaz64 is on the money. Fuel will only drip out the booster until it reaches the level in the float bowl. If the needle & seat are not operating correctly, fuel will continue to be pumped into the float bowl and out the boosters (though the metering plate). If this has been going on, your oil may have an excess amount of fuel in it, reducing the oils ability to lubricate
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Pulled the carb off and pulled the float bowls. The needle still feels springy, and the gaskets (holley blue) still look OK (although I will replace them anyway). How can I tell if my float still floats? Do I need to pull the float out of the bowl (seems to be attached in the bowl with two star-head screws).
Thanks, JLW |
JLW -- the blue gaskets are reusable; usually several times. But, wtf, if in doubt go ahead and replace them. The only way a float ever goes bad is if it has a hole in it. I haven't seen a hole in a Holley float in a long, long time. But the way we tested them when I was younger was to take them out and put them in the tub with the tub full of water. Let them sit there while you eat a sandwich, then take them out and shake them. If there's water in them they're bad. If not, clean them off well and reinstall.
EDIT -- Put them so they stay under water, don't let them "float" on the top.... |
If you have the black nitrophyl floats, the surface can become nicked, or damaged allowing it to become soaked with fuel and heavier than it is designed to be. If this is the case it has to be replaced.
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Does the needle and seat work as a needle and seat, or is it bypassing fuel?
Is the o-ring on the needle and seat ok? Will give same symptom. Weigh the floats, if the secondary is heavy, it's fuel logged. |
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A blown power valve feeds fuel directly to the intake manifold, via the vacuum channel in the throttle body. The bowl drains into the motor at shutdown. Excessively high float level IS THE ONLY WAY fuel can run from the boosters. All carburettors will have this problem with an uncontrolled float level. |
Guess the Holley books are wrong... I'll call the factory and tell them.
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You could have .150 mains and .090 pvcrs that are open to the main well (if for laughs, the power valve vacuum port was blocked off) and the engine will still idle unaffected by the main circuit. Fuel will NOT discharge from the boosters until airflow through the venturi creates a strong enough signal, of which there is none at idle; it will only discharge if the fuel level in the main well is at the height of the booster fitting in the mainbody. The fuel level in the main well is the same as the wet level in the float bowl at idle/low speed. |
Hold on. Before you go ripping things apart, take the back of a screwdriver, (the one you are going to use to set the floats and adjust the idle) and tap the top of the needle and seat. {good taps) you are not going to break anything. Then try again. This usually loosens the needle from the seat. It could be debris but usually just a sticky ingredient in the gas that has dried. I've seen this alot in race cars that sit.
Lou |
So I did have a sticky needle valve, but now that that appears sorted, it looks like the float in the secondary bowl doesn't push the needle up far enough to close off the passage. When I blow through the fuel inlet on the primary bowl and push up on the float, air flow gets closed, but when I do the same for the secondary bowl, air still gets through.
I was thinking as I typed this that I had a float problem, but could it be that the needle valve isn't seated deep enough for the bowl to push the needle to the full closed position? Thanks, JLW |
The float should close the needle valve way before it hits the roof of the bowls. Usually about 1/2 from the top of the float to the roof of the bowl. Don't force anything or you will just bend the lever. Replace the needle and seat, quick adjustment is to set it about 1/2 from the top of the bowl.
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It sounds like you need to adjust the float on the one leaking. Be sure there is an "O" ring on the brass threaded part that threads into the float bowl casting.
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So your secondary inlet valve is faulty, or not seating because of debris OR the seat o-ring is faulty.
At least it is not related to a blown PV, which most of us knew would be the case. |
Ok, $^&#!
The summit box arrived this week with new float needles and gaskets. I put the new needles in, and verified that I couldn't blow air through the fuel inlet of the bowl when I manually pushed the needle closed (bowls removed). I then replaced the bowls, and on the primary, pushing up on the bowl also closed off air completely. On the secondary, I had a tiny bit of air coming through, but not like before. Impatience got the best of me, so I buttoned everything up and put the carb back on the car.
And as soon as the bowls were filled, here comes the flood again, and this time, through the primary boosters too! On top of that, it looks like I've got a leak in the secondary accelerator pump - on top of fuel pouring into the carb (and even a burp of fuel through the bowl vent), fuel was leaking out of the bottom of the secondary (happily not the primary, though). It SEEMS like the next thing to do is replace the floats now (and the accelerator pump diaphragm), but I'm to the point of giving up and handing it over to professionals (Cooke's Automotive (Austin) is around the corner from us, and has treated the Cobra well for past problems, even tuning the carb idle for free when it was in for a brake problem). Thanks again for all the help - JLW |
Are the floats the same weight and construction?
Are the needle and seats the same size? .110? Did you adjust the floats for a low level, then bring them up while checking the levels with the motor running? |
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