This is topic Why is my carb motor running rough? in forum Tech Talk at Northern California Ford Owners  .


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Posted by BCINGUU (Member # 2397) on :
 
My 67 stang with its original 289 motor is running rough and stalling at idle. It seems to be running very rich. I just removed the EGR and didn't seal the intake ports very well, so it's sucking air through those ports.

Don't know much about carb motors, but on an EFI system I know this situation would cause more air to enter the intake than what the MAF is measuring, thereby causing the ECU to spray less fuel than needed. This may result in a way lean condition possibly resulting on a lean misfire.

But on a carb motor? I'm guessing I need to seal up those EGR ports better or get some kind of eliminator. Does anybody know if there is such a thing? Who has eliminated their EGR and how did you do it? Is the carb tuned for the EGR and now not spraying enough fuel, just like in the EFI world?
 

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Posted by FasterDamnit (Member # 442) on :
 
For the Carb to meter fuel into the motor, the air has to go THRU the carb. Any vacuum leak will cause your symptoms.
 

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Posted by JohnB (Member # 969) on :
 
Re-seal the intake, use block-off tabs on the intake manifold gaskets and a block-off plate for the EGR port. Yes, your vaccum leak is causing the rich condition. And get rid of the 2bbl already!!


I've got a intake and carb ready to go here if you're interested. Weiand intake and a near-new Holley carb.
 

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Posted by BCINGUU (Member # 2397) on :
 
10-4 guys, thanks for the sanity check.

How the hell did you know I had a 2bbl John? ;D
 

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Posted by BCINGUU (Member # 2397) on :
 
dp

[ July 06, 2007, 12:10 AM: Message edited by: BCINGUU ]
 

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Posted by MustangNate (Member # 4559) on :
 
Because you said you had the original 289.
 

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Posted by BCINGUU (Member # 2397) on :
 
Ah, the process of deduction, Watson.

My problem is resolved, thanks again gentlemen.
 

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Posted by FasterDamnit (Member # 442) on :
 

quote:

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Originally posted by MustangNate:
Because you said you had the original 289.

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quote:

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Originally posted by BCINGUU:
I think they had different options. Mine is indeed 2 bbl.

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A code vs. C code.
 

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Posted by 90lxfoxbody (Member # 6947) on :
 
67s had egr valves ?
 

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Posted by BCINGUU (Member # 2397) on :
 
Yeah, and a smog pump too. Guess they started the emission stuff early.
 

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Posted by 2stangs69-91 (Member # 1951) on :
 
first off a vacuum leak on a carb car will NOT cause a rich condition. I agree also on swaping on a 4barrel carb. good luck. But a vacuum leak will cause your car to die at idle. Good luck.
 

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Posted by Camaro Kid Z/28 (Member # 3100) on :
 
theres no way that car came with an EGR vavle, smog pump yes,Nox box yes indeed!
 

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Posted by BCINGUU (Member # 2397) on :
 
I had a big vac leak and when I plugged it everything was fine. I think the car went way too lean, resulting in a lean misfire. Not a rich condition but a lot of unburnt fuel getting out.
 

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