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shaking and sputtering engine

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Old Oct 31, 2011 | 04:48 PM
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Default shaking and sputtering engine

Hey guys,
I was hoping for some insight on a problem that I have been having w/ my 1978. Upon starting the car, the engine sputters, and shakes bad enough to shake the whole car. It takes the car a very long time to warm up, once up to temperature, it runs smooth. Just today, it died out on me on the street in front of my house, and would not restart. The car cranked/turned over, but would not start. It had a bad case of the shakes, before it quit running. Any insights would be appreciated.

Thank You,
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Old Oct 31, 2011 | 04:55 PM
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When did you last give it a tune up?
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Old Oct 31, 2011 | 05:15 PM
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I haven't tuned it up yet. I just oil changed, and did the greese/oil/filter. I did not change out the plugs or plug wires yet. I just bought the car a few months ago, this is the first problem that I have had.
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Old Oct 31, 2011 | 05:26 PM
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How long has this been going on?
If it just started getting bad when the temperature dropped, check the choke pull-off.
If its working correctly it will open your choke plate slightly after the engine starts.
If its nonfunctional you will get the kind of behavior your having until the car warm up enough to open the choke.
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Old Oct 31, 2011 | 05:30 PM
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Pretty broad set of symptoms. I agree that the choke is the first thing to check - and it's easy
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Old Oct 31, 2011 | 05:35 PM
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During the oil change, I did look at the choke plate during the warming up stage. it opened slightly while cold. It did not fully open, even after the car ran for a while. I noticed that the hose that connects the choke tube was torn. I put another one on. It was not temp resistant, but I could not find one anywhere. Maybe this is the problem?
And yes, this is a new problem since the weather has been cooler.
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Old Oct 31, 2011 | 06:03 PM
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I have to agree with the choke. Make sure the butterflies are opening and closing with ease. If they hang up you can adjust them a little by loosening the screws and adjust the them so they open and close with ease. It might be that it needs to be cleaned with a cleaner. If you adjust the butterflies make sure you don't take them all the way out and drop the screws down the carb.

Ron
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Old Oct 31, 2011 | 06:13 PM
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Thanks, I will try that.
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Old Nov 1, 2011 | 06:06 PM
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I loosened the butterflies, but it still seems as though they are not opening all the way. When I manually open the butterfly, the shake goes away. Don't know why it does not open up by itself???

Also, I noticed some black soot that blows out of the exaust pipes after I start the car. I can see it on the garage floor. Should I be concearned with that???

I am not mechanically inclined, but am trying to learn through this experience, working on my vette. Any help is greatly appreciated.

Thanks
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Old Nov 1, 2011 | 11:47 PM
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Originally Posted by rv1978
I loosened the butterflies, but it still seems as though they are not opening all the way. When I manually open the butterfly, the shake goes away. Don't know why it does not open up by itself???

Also, I noticed some black soot that blows out of the exaust pipes after I start the car. I can see it on the garage floor. Should I be concearned with that???

I am not mechanically inclined, but am trying to learn through this experience, working on my vette. Any help is greatly appreciated.

Thanks
Sounds like a classic case of the choke not opening up enough, or fast enough. If I am correct, the '78 'vette had a hot air choke, it drew hot air from a tube that came off the back of the carb or from inside the air cleaner, (in order to draw clean, filtered air) went down inside the intake and got heated by the exhaust crossover passage, came back up and went to the choke, heating it. If that line is clogged or broken or leaking or missing, the choke won't heat up properly, making the engine run rich. Eventually, it will heat up and run normally. That also explains the black soot when first started.

Un fortunately, I can't look at and mess with your choke from here, but now that you know a little about how the choke works, you may be better able to figure out what's going on here. Good luck,


Scott
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