stumbling, hesitation, surging, stalling 69er (vacuum leak?) - Team Camaro Tech
Troubleshooting Diagnosing problems done here.

 
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post #1 of 9 (permalink) Old Apr 18th, 00, 05:57 PM Thread Starter
 
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Ok heres the story. I rebuilt my holley 600 carb (9834-3 its a 4160) 2 weeks ago with a holley trick kit. It car ran just fine before I rebuilt the carb, I was basically replacing the leaky gaskets and used the new items anyway.

Anyway the floats are level just seeping out the sight holes,
drivers idle mixture screw is 1/2 turn out and passenger screw is 3 turns out to get highest vacuum reading and smoothest running (thats kinda weird whats up with that)

These are the symptoms:
shaking/stumbling at idle (not missing), hesitation, popping out the dual exhaust, surging, and if I really lay on it it will stall from a dead stop.

I called holley and they didnt help any. I went up from a 31 to a 35 discharge nozzle to help the hesitation- it did nothing. because it is not the problem you can feel the car shake hard at idle.
I got to thinking it would be a vacuum leak, tested (18 points at idle)and thought I found it the problem. I temporarily plugged it, Test drove it and drove better than new... until I hit the driveway, all the simptoms were back. I then took the carb off and siliconed the hole base gasket. tested vacuum and was up to 22.5. test drove and worked fine. drove a day or two and simptoms coming back a little. vacuum is now 21. it finally bottomed out at 20. I spray and try to find another leak and find nothing!!! What is going on here, It plugged the leak twice and ran good for just a very short time.
It is driving me nuts. I am at my whits end and about to pull my hair out!

Holley and some other people I talked to said its a lean condition but that tells me nothing.
It is not the accelerator pump. because it shakes at idle (nothing to do with the accelerator pump) and its not the floats, they are level, I just replaced the fuel filter, have good fuel pressure.

Whatever it is it is in the idle circuit or vacuum leak. but I cant find the vacuum leak?!! I have plugged and tested everything a million times. I have the carb off and apart now and see nothing out of ordinary.....
please help... Any other way to vacuum leak find? email me or reply here

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69 Camaro 1977 350
Shift kit, Pertronix ignitor
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post #2 of 9 (permalink) Old Apr 18th, 00, 11:57 PM
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Dave
 
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Have you checked for hairline cracks on the PCV valve hose? Power brake hose, retorqued the intake? retorqued the carb bowls? Checked that the secondary throttle plates on the carb are closing all the way. Do you have an EGR valve? Is the mechanical & vacuum adv on the distributor working smoothly.
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post #3 of 9 (permalink) Old Apr 19th, 00, 06:32 AM Thread Starter
 
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I have checked for cracks, I have replaced all vacuum lines (to distributor, pvc, tranny)
Intake is nice and tight, secondaries are closed all the way, no egr. And the mechanical and vacuum advance seem to work fine
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post #4 of 9 (permalink) Old Apr 19th, 00, 07:13 AM
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If she coughed once out the carb, you probably blew the power valve. It operates on vacuum and if bad will give you the symptoms you are describing. Thats why I went to an Edelbrock carb.

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post #5 of 9 (permalink) Old Apr 19th, 00, 09:47 AM
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Law,

How much did you torque on the bowl screws? An old timer ex racer once told me that over tightning of them is one of the most common probs on these carbs as it will worp the plate DUNNO
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post #6 of 9 (permalink) Old Apr 19th, 00, 10:11 AM
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this is a mistake i made my first time...i left a gasket on the primary 1/2 off( big leak) popped, and spit fuel out the exhaust,(lucky no fire)it was the valve thats stop sign shaped<---don't remember name..duh...lol

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Doug G.
68 Camaro
406 ci.

[This message has been edited by DOUG G (edited 04-19-2000).]

[This message has been edited by DOUG G (edited 04-19-2000).]

[This message has been edited by DOUG G (edited 04-19-2000).]

[This message has been edited by DOUG G (edited 04-19-2000).]
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post #7 of 9 (permalink) Old Apr 19th, 00, 12:27 PM Thread Starter
 
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Ok get this.... I took the carb all apart and put it back together again..... drove 25 miles, running just as crappy as normal. picked my brother up, turned the car on and it stumbled then it smoothed out and went up to 1400 at idle.... The problem was gone. I drove around and decided to go shopping and see if the prob would come back. in all I drove probably 60 more miles. No problem..... What the he!! I hope it stays gone
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post #8 of 9 (permalink) Old Apr 20th, 00, 03:59 AM
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Thumbs up

Murfys_Law, Glad ta hear


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post #9 of 9 (permalink) Old Apr 22nd, 00, 02:37 AM
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damn pesky gremlins....gotta hate them.but congrats anyway.

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