Ocassionally I get this annoyingly LOUD buzzing noise coming from the carb, I'm not sure why or how but it sounds like one of those new years party favors that everyone has except it never ends for a whileeeee. It only does it while idling never while reving.....and its only happened twice...anyone experienced this before??

 

I've heard a similar (I think) noise in an Olds 307 at low idle, not LOUD but clearly audible, which I attributed to a worn out cam chain or something. I just turned up the idle slightly. I don't know how the carb could make such a sound. Maybe worn-out bushings?

 

A CCC carb is SUPPOSED to buzz. It has a mixture control solenoid that the computer pulses. It's supposed to sound like a new year's party favor. It's not a worn out timing chain and you don't need to turn the idle up. It's active mostly at idle, which is why you hear it.

 

Really, thats interesting. Its supposed to buzz clearly and steady, it doesn't happen all the time in fact this is the second time in 4 weeks of steadily running it.

 

It should always be buzzing at idle. The speed/pitch of the buzz will change depending on engine running conditions and whether you are closed/open loop.

 

I wouldn't call the fast klicking noise from the Mixture Control Solenoid for a buzz..
It has a fixed frequenzy of 10 Hz (clicks per second), with a varying loudness depending on which duty cycle the ECM commands, and it's active all of the time the engine is running. It's hard to heard over the noise from the engine, unless you put your ear to the carb or has an unusually quiet engine.. Some ECM's run it as soon as you turn the key on, others wait until you crank it. If the MCS sticks or quits for some reason you would at the same time notice a change in the idle quality of the engine, and mileage would be affected. It's connected with the plug on the top of the carb. Disconnecting it will set the Check Engine Light, the engine will run rough, soot, and get lousy mileage.

 

Alright that clears things up, yes I know of the clicking noise you speak of its not loud at all, I hear that the second I turn the key before starting the car but only if the hood is open and I happen to have the key turned and the car not running w/ me under the hood.

The buzzing noise I hear is much louder then the engine and sounds like a kazoo more or less but at a steady tone which can be heard inside of the cabin. I read elsewhere on the site w/ someone else having this problem and it was due to a faulty alternator. Something to the effect that when the alternator or battery goes it causes the choke light to come on and the choke doesn't get the power it should get which it requires a steady 12V and so the choke closes w/ no power and that in turn causes the buzzing noise. Anyone know of that or how much of that is true?

 

Ok, thats good, one thing out of the way..
The noise I heard in the 307 was kazoo-like and heard well above the other engine noises (with hood open). Never diagnosed exactly what it was but I know that car has put a lot miles behind it since then without any issues.
If the choke comes on (a slow thermal process) then the fast idle cam would have effect as soon as you thouched the gas pedal, and I never heard about the choke flap making noises, so I don't think it has anything to do with this.
So you have clearly located the noise as emanating from the carb?
A worn-out bearing in the alt could make such a noise but I guess it would be more constant.

 

I'm probably not gonna find the culprit until I actually start replacing parts until I hit it. Its so loud its hard to locate....it sounds like is right behind the carb to be honest...but I know the alternator is not powering the car enough and I know that the alternator is supporting the full electrical load of the car as the battery is not holding any charge. So I'm gonna change the battery next week sometime and see how that effects everything, then move on to the alternator and if the noise is still happeneing after that then I'd have to bet on something mechanical I guess or vaccume perhaps.....I'm betting on electrical cuz it doesn't happen w/ a charger attached to the car.

 

Id guess at a small vacuum leak. I had a gasket blow out around an adaptor plate and it sounded like a kazoo with 90 PSI air going through it. Very loud. Get a section of heater hose, put it to your ear, and start moving the open end around to locate the noise. Does it go away when you give the engine throttle?
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Definatly a vacuum leak. Check carefully around the base of the carb.

 

yes it does. Happens randomly while idling. Only twice in 4 weeks and it goes away while reving once it hits roughly 1500 rpm's it starts to come back then the engine settles to 800 -1000 rpms depending on the condition and thats when you hear it.