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Old 10-02-2002, 11:51 AM
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Post carb problems on 84' Olds 307

I've got an 84 Olds Custom Cruiser wagon with a rebuilt 307 and tranny (84 being the last year for the Y code 307 with the 5A heads.) with around 154K original miles. The engine starts right up and runs real strong, but the engine idle is just a headache. Figuratively, it sounds like the engine's got emphysema, like it's choking or somethin...lol Its loud, distinct, and has an almost diesel-type-of sound. The noise does seem to be coming from the carb, though. (in fact, with the engine firing, the whole carb shakes a little especially if you give it gas) I checked the carb just the other day, and no, it isnt dirty. (the first thing I suspected) Not too sure what could be wrong with it, except maybe its time for a new carb. Do these factory Q-jets hold up to 155K? Could this be a worn gasket perhaps? Any help yeilded is appreciated.

Thanx,
~John~

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Old 10-02-2002, 04:12 PM
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Is the carb loose from the manifold or the bowl loose from the baseplate?
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Old 10-02-2002, 05:35 PM
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Is it a feedback carb? CCC GM?
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Old 10-03-2002, 09:07 AM
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I'm not too certain if the carb is loose from the manifold, or the bowl from the baseplate. If perhaps you could tell me how to discover if this is so, I can have my mechanic friend pop it off and have a look at it. (that is, if removing it is required)

Is it a feedback carb? CCC GM? Personally, I don't know what a CCC GM is. Maybe you could explain that to the newbie here...lol
Not sure about the feedback carb either. As far as I know, it has the factory 4bbl carb equipped with the Y Code gasoline 307. I'd always thought that carb was a Q-Jet, but then as you can see, I'm not quite as in-the-know as you guys, so perhaps you can enlighten me here.

Thanx for the help,
~John~
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Old 10-03-2002, 10:48 AM
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The sound you are hearing is probably a clicking sound from the idle compensator, this is adjusted from the top of the carb under an aluminum plug. I'm sure you probably have an electonic Q-Jet, it has an idle compensator, a rich stop adjustment, and a lean stop adjustment as well as a Throttle position sensor. A bad throttle position sensor will cause the carb to idle very roughly, as will bad orings on the rich stop emulsion adjustment. These carbs are kind of tricky to get to run right. Check for vacuum leaks, and proper spark at every cylinder.
You need to find someone with a good scanner, and test a few things first, if the carb is suspect, I would find a professional to help you with this carb, as it is a testy rebuild.
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Old 10-03-2002, 12:39 PM
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[quote]
  • Its loud, distinct, and has an almost diesel-type-of sound. The noise does seem to be coming from the carb, though.<hr></blockquote>

    That may be the pulse type emission system as the exhaust hose is vented to the air cleaner housing. Makes one heck of a noise when the lid is off the air cleaner.

    [quote]
  • (in fact, with the engine firing, the whole carb shakes a little especially if you give it gas)<hr></blockquote>

    That's why you were asked if the carb was secured properly to the intake manifold. There are four caps screws that hold it down. Are they torqued properly?

    [quote]
  • I checked the carb just the other day, and no, it isnt dirty. (the first thing I suspected) Not too sure what could be wrong with it, except maybe its time for a new carb.
<hr></blockquote>

Well, being a CCC carb, you are going to find exchange carbs run anywhere fron $300.00 to $1400.00 (depending on source and quality).

As previously stated, the carb is controlled by the ECM and supporting sensors. You will need a scan tool and supporting repair information unless you luck out and it is merely a mechanical problem.

Again, a vacuum gauge is a mechanic's best diagnostic tool.
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