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Old 09-03-2008, 08:18 PM
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carburetor trouble

Hey guys this has been a wierd night. A buddy of mine stoped by to see how my car was coming along and when i went outside to fire it up for him, it wouldn't start unless i held it to the floor. Then when it did start, it wouldn't idle.
Let me back up a little. The carb is a holley 600cfm street carb, I'm pretty sure the part number is 80457. The other day i was doing a little tuning on the car at operating temp, I was trying to find the sweet spot between the carb and timing that would allow it to shut the key off and fire it right back up with out touching the pedal that much.
When i walked around the the front I seen Fuel all over the intake, it was bubbling out between the main body and the metering block. I thought the mabey i didn't have the bowl bolts tight enough so i tightened them down and it quit bubbling out. Then I drove down the road to my dad's and he wanted to hear it and i needed an extra hand to help me set it (in gear, holding the brake, ect). He opened the A/F mixture screws up pretty far and took some advance out and raised the idle on the screw a little. Everything was going good, it was right where i wanted it, i could turn it off and start it back up with out touchin the gas, it wasn't dying in gear. I let it cool down for about 4 hours to see how it would do cold, and it started right back up and pulled back into the garage just fine.
Now back to today. The thing is acting crazy, one minute i can start it up and it perr's like a kitten as smooth as can be, then if you touch the throttle it drops the idle so low that it dies (cold and hot temp makes no difference). then it will start raising the rpm with out touching anything. When you think you got it close enough to try to put it in gear, i did, and it dropped idle (as expected) but stayed running, but then when i put it back in park it the idle didn't come back up as it should have. It's as if i have no adjustability on it, and its just doing whatever it wants to do.
Does anyone have any ideas on what could be causing this? let me know if you need any more info about the syptoms.

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Old 09-03-2008, 08:43 PM
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By the way it sounds either you have the float level too high, trash in the needle and seat or excessive fuel pressure. With the car at idle and the air cleaner removed, shine a light in the primary side of the carb, if you see fuel dripping out of the boosters, you have one of the three problems mentioned.
If you don`t see any fuel dripping out, shut the engine down by pulling the power wire on the HEI, if you see excessive while smoke come out of the carb, again, you have one of the three issues but instead of it coming out of the boosters it`s overcoming the idle circuits, this or the fuel drippage from the boosters is whats causing the carb not to respond. it was also likely the cause of the fuel on the intake. Check to see if it`s holding pressure after you shut it down, it should not hold fuel pressure after it`s shut off, if it does you have a vent problem in the fuel system, which will also cause excessive uncontrollable fuel pressure problems. What`s the fuel pressure? it shouldn`t be over 5 psi.
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Old 09-03-2008, 09:09 PM
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carb trouble

Well, i don't have a gauge on it so i really don't know for sure. It does have the White smoke rolling out when i shut it off. Looking down in the barrel, it looks as though it is just shooting a straight stream of gas only and not mixing it at all. Nothing comes out of the boosters at idle period. When i give it gas, a A/F mixture comes out of the boosters on the front of the carb, but it doesn't look "normal" it almost looks like thier obstructed and having a hard time pusshing fuel from them. The rear is dripping like you said, until the four barrel opens then it sprays.

I'm at work now so i really can't do anything to it till i get home tommorrow morning. But i just had a thought. My gas gauge doesn't work yet, and i know i didn't have very much in it before i went for a ride. Could it be almost out of gas? Would that cause these things to happen?

It seems to be definitely related to the pressure, because it is surging up and down like one second it has fuel and the next it looses it.
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Old 09-03-2008, 09:20 PM
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Uncontrollable idle makes me think of a vacuum leak... or maybe a sticky or malfunctioning vacuum advance? Of course that doesn't explain the fuel bubbling out of the carb...

Last edited by Sir Joab; 09-03-2008 at 09:39 PM.
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Old 09-03-2008, 11:36 PM
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You should not have fuel dripping out of any boosters at idle. As Doublevison says, you may have rubbish in your secondary needle and seat, the rear float may be misadjusted, or the fuel pressure is too high and forcing past he secondary needle and seat. Pull the needle and seat out, look at it closely to see if any debris is on it. If it is new, clean it and reset your floats.

When revving the throttle fuel in "park" you should only see fuel squirt out of the squirters, nothing out of the boosters.
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Old 09-03-2008, 11:52 PM
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revved in park???

You say i should see nothing out of the boosters in park?? How do i fix it then cuz there is definitely A/F coming out when revved in park, and the rear is definitely dripping. I had some trash in it a few months ago but i pulled the bowls and cleaned the needle n seat out. I actually seen the trash come out. I put it back on and it did well till now, but thde rear has always dripped and iv'e always had the spray in park even when it was running good. Is this wrong should i not have this. If so, how does the fuel mix?
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Old 09-04-2008, 12:10 AM
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Quote:
Originally Posted by eatonde
You say i should see nothing out of the boosters in park?? How do i fix it then cuz there is definitely A/F coming out when revved in park, and the rear is definitely dripping. I had some trash in it a few months ago but i pulled the bowls and cleaned the needle n seat out. I actually seen the trash come out. I put it back on and it did well till now, but thde rear has always dripped and iv'e always had the spray in park even when it was running good. Is this wrong should i not have this. If so, how does the fuel mix?
First thing first, are you looking at the booster or the squirter??? The boosters are in the center of the throttle bores and attach to the carb body with a downleg or straitleg. If it's a 4-barrel Holley you have four of them. Next, squirters screw into the carb body, there should be two on a double pumper and only one squirter on a vacuum secondary carb.

Boosters should not drip at idle or shoot fuel when revved in Park. On the other hand, squirters will squirt a stream of fuel when revved in Park. Leaking boosters will sometimes flood the carb body when parked and the engine is off and will cause hard starting as you are flooding the engine because fuel is pushing past the needle and seat. If overly full, fuel may even flow out of the vents. Verify by checking the plugs....black or wet???? Boosters normally get activated under load and are fed by your main jets. Your main jets are normally not active while in Park.
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Old 09-04-2008, 12:38 AM
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If it helps, here's a pic.
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Old 09-04-2008, 07:45 PM
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boosters and squirters

Yea i was saying it the right way, i didn't have them mixed up. Yes the primary boosters are spraying in park if revved up, but not at an idle. and the secondaries boosters are dripping. I suppose i will pull the carb bowls and remove the needles and clean again. However, 3 days ago the car was running fine with the dripping from the secondaries. If it is "trash" in the carb causing the problems, how do you think it would have gotten into there with out the car being ran??? It was running fine when i put it in the garage. I even shut it of and started it back like 4 times before i left it just to be sure that the tuning i did actually worked and i had no problems.
It almost feels like i've been sabotashed (spelling????). Is it possible that its just so low on fuel that its getting some one second then losing it the next cause its just barely slurping it from the tank. I haven't had a chance to put more gas in the car to test this yet, but is it a possibility. I know it's not whats causing the dripping from the secondaries but could it be what is causing the idle to "surge" up and down and be uncontrolable?

Just for my own curiousity, How does the carb know whether the transmission is in park or not to activate the boosters?? I'm not questioning you, i've just never heard that before and wundering how this occurs??
Thanks, Danny
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Old 09-04-2008, 07:53 PM
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What gear the tranny is in has nothing to do with it. The primary or secondary boosters drip due to the reasons I already posted. I will also ask, did your vehicle come with a carbon canister you removed and plugged the line? if so, the line is a vent line and it must be open or the fuel tank will build excessive pressure. If you do not have a fuel pressure gauge get one, it`s shooting in the dark without it. Trash can get to the needle and seat easily, if a vehicle sits for over 6 months and the fuel turns into trash and you can`t even see the trash that gets into the carb. been there done that and don`t wanna do it again. It don`t take much for it to make the needle stick open in the seat and cause the condition your having. Since fuel is dripping out of the secondary boosters at idle thats why you can`t tune it. Since it`s getting fuel from a alternate source other than the idle circuits it`s not supposed to be responsive to adjustments.
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Old 09-04-2008, 08:28 PM
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carb trouble

Thanks D/V. I didn't think it should make a difference what gear it is in, but what is tubbedz talking about when he says the boosters shouldn't spray while in park. Thats what i was asking about. I don't understand how or why it wouldn't come out of the boosters in park just as it would in any other gear. or why it would make a difference.

So i should go ahead and try and reclean the needle and seat and fuel bowls to try to stop the dripping secondaries. Then what about the carbon canister? I don''t know what or where thet is. How do i know if it has been removed, but i do know that the gas cap i have i supposed to be like a self venting cap to keep the pressure from building up.

What about what you said about the white smoke coming from the carb(when it dies). Will cleaning it take care of that too, or is that a seperate issue?
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Old 09-04-2008, 09:23 PM
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Could have sucked up some junk off the bottom of the tank cuz its close to being out of fuel. Pull the bowls and have a look for junk. You have to get the carb to stop bleeding fuel into the motor at idle before you should adjust anything if you dont the adjustments you make will take you in the wrong direction. The idle mixture screws are turned way out you say....they should be out no more than 2 turns. Start fresh, clean it up, set the floats, idle and fuel pressure then tune it. And while your at it change the fuel filter....it may need it.....Hope ths helps...Lorne
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Old 09-04-2008, 11:20 PM
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The fuel that you see coming out of the boosters are probably the overflow fuel going past your needle and seat. This video shows the drip.

http://www.youtube.com/watch?v=WrASQwz1oRc

As doublevision says find out what is causing the carb to drip. The following video shows a two barrel that is revving and the only wet fuel you see is squirting from the squirters.

http://www.youtube.com/watch?v=F20rf3ZbxiU

Sorry I confused you about the car being in Park but, I can't fully explain to you in this Forum the fundamental workings of a Holley. I've been working on them for over 25yrs and to explain this would be writing a book. In simple terms, idle fuel is sent via holes in your baseplate and metered by the idle mixture screws and air bleeds. As you open the throttle a transition is made. This transition squirts fuel from your squirters then the jets and boosters come into play. The suctioning effect of the throttle plate open will draw atomized fuel from the boosters. If you need more information read this book from Dave Emanuel titled "Super Tuning and Modifying Holley Carburetors".

When I was younger I was in your same situation. I couldn't figure out a Holley for the life of me. One day, I met a bunch of older rodders and they "schooled" me on Holleys, engines, transmissions, welding,etc..... nowadays my tinkering is over and all I do is read.
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Old 09-05-2008, 11:53 AM
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This page will explain the basics about Holley tuning. Hope it helps.

http://www.bob2000.com/carb.htm
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Old 09-05-2008, 01:51 PM
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thanks

thanks to all, i'll do my best to see if i can get her lined out this weekend. I'll give you guys an update on monday. I'll get back with ya if i have more ?'s
thanks, Danny
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