Has anyone had a bad alternator cause a weird misfire at idle, almost like the car is not sparking properly? I’ve upgraded to pertronix, replaced coil, plugs, plug wires and cap. Carburetor replaced twice. Still idles like absolute crap at idle. There are no vacuum leaks, believe me I’ve checked 8.2 million times. The vacuum booster is good. The compression is good. The carburetor has been adjusted every which way from Sunday. To no end sit at a light and idle and it gets worse and worse. Step on the gas and off she goes with no effort. This ones got me stumped! Only thing I can think of is a alternator going bad. It seems to charge fine and no generator light while running. Has anyone else experienced this. I’m running out of ideas.

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I’m shooting  in the dark here,  How about the steel shim on the bottom of the carburetor?  The order of the gaskets on the bottom of the carb ? 

It’s a Rochester, it has a gasket on the manifold, the plastic spacer, another gasket and the carburetor.

Fuel pump pressure ? Crap in the tank ? Crap in the filter ? 

Good pressure, clean tank and new filter.

Hey Tom ,look in the right hand corner search box and put in the words  “steel shim”  you’ll see a post about not running right , read that post maybe it can help you with your problem or put you in the right direction, good luck 

 Ray, He indicated he had the Rochester. The Rochester 4GC does not use the steel shim like the Carter AFB.  Have you set timing on the car? Did you run 12 volts direct to Pertronix? I know you said you have set the carb but you have to go back and forth beween the idle adjustment scews and air adjustment screw.  Unless it is something with the internal idle circuit in the carb things that have caused bad idle for me have been debris up in the screen inlet where the fuel line enters the carb, debris on the idel adjustment screw needle  end (completely remove and spray with carb cleaner). I don't think this has anything to do with the alternator.

I have been chasing this issue since the car had points. Pertronix was an attempt to correct the issue. Two new carbs in the past month and a half, I don't think its fuel system related anymore. Unless there is a weird problem with the fuel pump. I thought they either worked or didn't? Is there a way to test them? I'm more familiar with fuel injection. But I have enough knowledge to be dangerous lol.

Does the coil not provide 12v? 

No, The stock ignition coil receives a voltage usually about 9.5 via the resistor wire. The Pertronix Flamethrower Coils needs a full 12 volts. It is all in the instructions for the Pertronix Coil installation ... usually in bold print on 1st page. The ignition coil "provides" thousands of volts to the plugs via the distributor.  When you say "upgraded to Pertronix" that could mean the Pertronix Ignitor unit that replaces points, and/or the Pertronix Flamethrower ignition coil which replaces the stock igntion coil and requires a full 12 volts. If you simply replaced the coil with an OEM type coil you are fine, if Pertronix... you need 12 volts.

I see, I will have to revisit that when I get home this evening. Thanks for the tip.

Did you get rid of the condenser? 

I did, was I not supposed to?



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