Help, fuel pouring out of vent tube! - Team Camaro Tech
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post #1 of 8 (permalink) Old Jul 12th, 03, 12:49 PM Thread Starter
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Doing initial tune on freshly rebuilt 67 302. Everything bone stock & blueprinted, including the points ignition system and 3911 780cfm carb (4150 series) rebuilt by MacNeish.

I was having trouble setting the idle and discovered I'd installed the choke rod upside down and besides not operating properly it was binding with the fast idle cam. Fixed that, adjusted it "just right", checked the fuel bowl levels (fuel at bottom of thread), and tried starting up again.

Now, when I crank for a little bit and stop, fuel starts bubbling out of the main vent tube. If I crank for say 20-30 seconds, fuel is literally POURING out of the vent tube.

After cleaning off the intake and I open the sight plug on the main fuel bowl, fuel does in fact come out until the level is back below the threads.

What the heck did I do now?!?!?! Except for the choke/idle problem, everything was hunky-dory.
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post #2 of 8 (permalink) Old Jul 12th, 03, 01:02 PM
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DJ,
Sounds like a piece of "trash" got into the fuel line and is probably stuck in the needle and seat assebly, keeping it from closing all the way. You could try some carb cleaner in through the fuel inlet, but you will probably have to take the needle and seat out and clean it. This is not all that unusual with a Holley carb after a complete rebuild. Even the slightest bit of rubber from a new fuel line etc will stick the needle and seat open. You could also try tapping on the carb with a large screwdriver handle...sometimes that will dislodge the dirt.
Hope this helps,

Bill Koustenis
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Waldorf Md
1971 Chevelle "Heavy Chevy" original owner


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post #3 of 8 (permalink) Old Jul 12th, 03, 01:07 PM
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I agree with Bill, sounds like a stuck needle and seat to me... Another thought is too much fuel pressure??? But if your pump is stock I don't think that's the problem.

...Dennis

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post #4 of 8 (permalink) Old Jul 12th, 03, 02:50 PM Thread Starter
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Checked needle and seat, moves freely, seems clean. New filter should've caught any debris unless it came down thru the vent tube?

All I can think of now is the float is somehow malfunctioning. Thinking of pulling the fuel bowl as a next step. Doesn't look like rocket science, just four screws. Sure learning a lot about Holleys today. Plus, I can bench-set the float level before putting it back on. Not sure how to drain it first though...

Any other suggestions? Is there anything float-related on the choke side of the carb I might've screwed up while adjusting the choke and fast idle cam mechanism?
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post #5 of 8 (permalink) Old Jul 12th, 03, 03:33 PM
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Denis - If the carb is still on the car cut the top off a coke can (beer comes in bottles, right?) or water bottle so it will fit under one of the bottom float bowl bolts. Then loosen that bolt and let the bowl drain into the can.

Download the "Carburetor Rebuild and Adjustment Manual" holley has at http://www.holley.com/HiOctn/TechSer...o/FMCTech.html get the word doc as it has more info than the html version they offer. It will help with many adjustments... Also search on "holley" in the performance forum, there's a bunch posted that may help you.

...Dennis

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post #6 of 8 (permalink) Old Jul 12th, 03, 03:58 PM Thread Starter
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I think I found the problem. [img]graemlins/hurray.gif[/img]

I pulled the float out and I can hear the liquid sloshing around inside it--must be a tiny pinsized hole that's slowly been allowing fuel in since we first fired the engine last weekend. By today, it was full enough that the "float don't float", preventing the needle from ever seating.

So where can I find a new float assembly? Do I have to order direct from Holley or do places like NAPA carry this stuff?

Whew! Time for a beer.
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post #7 of 8 (permalink) Old Jul 12th, 03, 04:32 PM
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dj,
Thats pretty rare on a Holley ! Any local speed shop should be able to get you a Holley float. I would stay away from the ones that the normal parts stores sell, they never seem to be quite correct.

Bill Koustenis
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Waldorf Md
1971 Chevelle "Heavy Chevy" original owner


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post #8 of 8 (permalink) Old Jul 12th, 03, 05:40 PM Thread Starter
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I just remembered I had an old beater Holley lying around. Different series but when I checked the part #'s, the float bowls were the same. So I put the new float bowl on (from the beater carb) and problem solved!

Now, where did I put that beer? Oh, here it is. Hmmmm, good.
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