Originally Posted by Old442Head

another issue I had was my alternator starter a very faint whine and my battery light will be on only when cold. If unplugged the whine will go away so I'm pretty sure my brand new alternator is toast. Only happens when cold as well? Please share if anyone has had this very odd issue.

Originally Posted by shiftbyear

Loose that air cleaner base, Read this recent post from V8 Buick website. https://www.v8buick.com/index.php?th...t-away.363876/

Originally Posted by Olds64

Was it your alternator or starter that was whining? You can test the alternator with the engine running by measuring DC voltage of the battery. It should be charging at about 13.8 volts. Most auto parts stores will also test an alternator or starter either on the car or on the bench if you remove them.

Originally Posted by Old442Head

Just installed a newly refurbished rochester quadrajet, ran great for a week after tuning it in. Yesterday I stopped to fix the idle screw since I t was running a little high. Noticed that when I went to put the base plate of the air filter back on it would start running rough, and misfire a little. It even happens when it's 2 inches away so it's not air being blocked. I ran a ground from the negative batt to the intake with no luck. Only other thing I can think of is it's a vacuum leak at the base plate since it seems to be the front two bolts for the carb that are effecting it. Here is a post to a YouTube link. Also seems to only happen after it's warmed up, another issue I had was my alternator starter a very faint whine and my battery light will be on only when cold. If unplugged the whine will go away so I'm pretty sure my brand new alternator is toast. Only happens when cold as well? Please share if anyone has had this very odd issue. https://youtu.be/TU8HBLZ_mGU

Originally Posted by Vintage Chief

(2) The alternator itself is incorrectly wired in your electrical circuitry. I have a '71 CS not a '74, I suspect your alternator contains an internal VR. Make certain you have your alternator wired correctly into your circuitry - double-check any suspect wiring. Make absolutely certain your alternator is designed for your application - not horrendously overrated, and absolutely installed into the circuitry correctly;
(3) Your distributor. You have an HEI installed or contact points? Make absolutely certain it's installed correctly;
(3) Your IGN coil. How is it mounted, where is it mounted, are any wires not wired correctly, is the IGN coil the correct coil for your application?;
(4) Your IGN coil wire. Is it loose, brand new, old, or whatever?;
(5) Make absolutely certain every single power (positive) wire is completely insulated.

Originally Posted by Vintage Chief

(6) Examine, remove any extraneous component wiring which is not germane (a common) component to the electrical system...

Originally Posted by Vintage Chief

Here is my take. I've watched your video numerous times. The first time you place the base plate of the air cleaner over the carburetor the vehicle begins to run rough WITHOUT touching any metal. Am I correct with regards to what I am witnessing in this video? You haven't even touched the base plate to metal, but simply placing the carburetor base plate over (in fact, perhaps near) the carburetor the engine begins to idle roughly. Is this correct? You stated it happens when it's 2" away.
Yes or No

This is certainly a very peculiar phenomena , but not completely without an answer. Determining the answer requires some basic understanding of electricity and more importantly "electromagnetic induction". I'll bet you have a basic understanding of where this is heading, but I have never seen what you're describing on any automobile - which does not mean it isn't possible. I'll leave the whining alternator out of the equation for a minute, but I have my suspicions the "direct" cause is most likely not the alternator, but the alternator might be a contributing factor.

In basic terms, it appears to me you are inducing an electromagnetic potential between two opposing electrical charges, what can best described as an interrupted electrical flow or "eddy". These eddies would/should normally only occur in an AC circuit, where the current flow in both directions - moving in one direction the majority of time, but reversing in the opposite direction during specific intervals; albeit, alternating current. A DC current would not normally be suspect of creating an interrupted electrical "eddy" since the direction of flow is in one direction only.

All electrical devices produce (at the very basic level) an alternating current when you convert mechanical energy to electrical energy simply through the creation of differences in electrical potential. Hang in there, you'll get where this is going. An alternator creates electricity and is designed to produce a large gradient of potential energy (and, so does your IGN coil). That energy (AC from the alternator) is then converted to usable energy on the vehicle in terms of DC. Diodes etc. will trap the backwards AC current and allow the current to run in one direction ONLY. One reason the creation of an eddy will most often never occur within a DC circuit.

Imagine you have a toy train, erector set, a small piece of electrical equipment (a tiny little AC motor) which creates a tiny amount of electrical energy to move the train or whatever. Now, take a magnet and place a magnet next to the tiny little electric motor which is producing this electrical energy. You will find the train slows down, then speeds up as you begin to move the magnet away from, closer to and at varying angles to the tiny little motor. Place two magnets - one on each side of this tiny little motor, etc. etc. This is what creates an interrupted electrical flow or "eddy". You can in many circumstances create this eddy with another large piece of metal held close to this tiny little electric motor. You have disrupted the electrical flow - that "appears" to be what is occurring in your scenario (only on a larger scale). The fact the alternator is whining (you stated only when cold but I'm suspect it happens all the time but you only "hear" it when it's cold, perhaps) demonstrates some suspicion - it should not be whining. Additionally, you stated the whining stops when you unplugged the alternator connector. However, you stated your alternator is producing a little over 14 V, which under any normal circumstance would indicate it's producing sufficient charging to the battery.

So, let's think about this a minute. You "witnessed" this phenomena occurring - you didn't even touch a piece of metal, you only held the base plate w/in 2" of the carburetor and the engine began to run rough. How is this possible? You disrupted the flow of electrical current (the actual electrical potential) somehow and somewhere. "Finding" the issue will be the mystery to solving this puzzle. I have my suspicions and I'll list them for you to validate on your own:
(1) The electric choke (if you have one installed) on the carburetor is incorrectly wired. To remove some doubt about this, you could disconnect the electric choke entirely to see if the issue resolves by repeating the base plate installation with the choke out of the equation;
(2) The alternator itself is incorrectly wired in your electrical circuitry. I have a '71 CS not a '74, I suspect your alternator contains an internal VR. Make certain you have your alternator wired correctly into your circuitry - double-check any suspect wiring. Make absolutely certain your alternator is designed for your application - not horrendously overrated, and absolutely installed into the circuitry correctly;
(3) Your distributor. You have an HEI installed or contact points? Make absolutely certain it's installed correctly;
(3) Your IGN coil. How is it mounted, where is it mounted, are any wires not wired correctly, is the IGN coil the correct coil for your application?;
(4) Your IGN coil wire. Is it loose, brand new, old, or whatever?;
(5) Make absolutely certain every single power (positive) wire is completely insulated. The disparity in electrical potential (interference to create this eddy) is going to occur on the positive side, not the negative side, IMO;
(6) Examine, remove any extraneous component wiring which is not germane (a common) component to the electrical system - just disconnect them to remove their circuitry from the equation.

Here's where I'm going. "IF" there is a disparity in electrical potential occurring (the creation of an "eddy") it would occur between two points (generally) or near to one point. Between two points i.e. between the IGN coil and the alternator, between the IGN coil wire and the alternator, between some left behind external VR and the wiring to the alternator (again, I have no idea if a '74 had an external VR), you probably did not buy this car new off the show room, I'd suspect any modifications by any previous owners are suspect.

If anyone reading this thread has witnessed this phenomena and knows of a corrective action to resolve your issue, they'd surely be speaking up about it. That's all I have. I'd be pulling my hair out, keep it simple the best you can - eliminate ONE variable at a time.

Originally Posted by Vintage Chief

I made a point (above) to suggest this is likely on the positive (power) side of the wiring scheme in the AC circuit and not the DC circuit.

Originally Posted by Olds64

Frayed wires with an exposed conductor and green corrosion are an absolute NO NO (as are wire nuts used in AC household wiring). This is probably right on track for the OP since he said the car had the wiring harness replaced.