Rough Idle 72 Cutlass

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Old May 23rd, 2008, 04:08 AM
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Rough Idle 72 Cutlass

If its the first time starting my car during the day I need to hold the gas down a little and kinda rev it so it doesnt turn off. If i let go of the gas it will just turn off. After i do this for a couple minutes and turn it off or drive it. Its fine for the rest of the day. Whats the problem?
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Old May 23rd, 2008, 04:33 AM
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Does your car have a choke?
How much do you have to rev it to keep it running?
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Old May 23rd, 2008, 05:12 AM
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Not to sure about the choke. Its a 74 350 4bbl quadrajet.

Dont have a tach so not sure on the rpms but just a slight steady pressure on the gas pedal keeps it alive. Let it go and it dies.
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Old May 23rd, 2008, 05:33 AM
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Sounds like either the choke coil is bad or needs to be adjusted. There should be a round housing on the passenger side of the carb with a black plastic cover (about 2" in diameter). Three screws hold the cover to the housing. Loosen the screws and you can rotate the plastic cover. Move it one notch towards rich and see if that helps. Failing that, there is also a fast idle adjusting screw on the carb. This is NOT the regular idle speed screw. If you're going to make these adjustments, you need to get a Chassis Service Manual or Rochester carb book to have all the diagrams in front of you.
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Old May 23rd, 2008, 06:06 AM
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Question

Simple test. With the motor cold, pull the breather off and see if the choke is open, or closed. It should be open. Pull the throttle linkage back, and the choke should close. "spring tension". get someone to start the car, and watch the butterfly valve. If it fires, then stalls, and the valve doesn't open, it's your choke pull-off, or the vacumn line to it..
Let us know what you find.

Last edited by Jim's rare 80; May 23rd, 2008 at 06:09 AM.
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Old May 24th, 2008, 02:21 PM
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So i have no other way to describe this but the car had a zip tie around something that controls the choke. i cut the zip tie and now the car starts right up and idles fine. what was the reason for that?
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Old May 29th, 2008, 03:22 PM
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too bad of description huh. soorrrry
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Old May 31st, 2008, 07:09 PM
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I have found that some previous owners of our classics never took auto shop in high school or anywhere else. I have found some very Mickey Mouse setups on the '72 Culass I bought last year. The upper radiator hose is tied to the support with a shoestring. ( I guess that was their budget at the time) I'm still finding little surprises as I go through this car. Joe was right on with the fast idle screw, although apparently that was not the problem with your car. I just recently put on a new Q-jet and had a rough idle as well. A little tweaking of the fast idle screw solved it. The repair manuals are worth the investment. Get an original GM manual if possible.
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