Stumbles when not warmed up - Team Camaro Tech
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post #1 of 8 (permalink) Old Sep 10th, 14, 06:10 PM Thread Starter
Rick
 
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Stumbles when not warmed up

Probably an easy fix with the choke but I'm not getting it right. Car is a 67 with a 327 and rochester quad carb. If I give it a lot of gas within the first 5 minutes of starting the car it stumbles and sometimes dies. The easy fix would be to wait until it is warmed up but sometimes I need to merge into traffic and can't wait. Any adjustments to try? Runs fine for hours after it is at operating temps.

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post #2 of 8 (permalink) Old Sep 10th, 14, 08:09 PM
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Re: Stumbles when not warmed up

I would suggest providing more information for the experts here (not me-I know enough to be dangerous) to help out. What type of choke, how is the carb set up and adjusted, engine timing specs, vacuum advance, what carb and is it new or old, rebuilt, more details on your typical starting routine?

The choke should activate with a single pump of the accelerator and then slowly open as the car warms up. Find out if that's happening first. The fast idle and choke need to work together for best cold starts and warmups and the idle and mixture screws need to be set correctly too.

Last edited by trland; Sep 10th, 14 at 08:19 PM.
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post #3 of 8 (permalink) Old Sep 10th, 14, 08:13 PM
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Re: Stumbles when not warmed up

Yes sounds like the chock is not adjusted properly and or the cold idle cam screw needs adjusting. (Its located on the left side by the choke.)


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post #4 of 8 (permalink) Old Sep 10th, 14, 08:54 PM
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Re: Stumbles when not warmed up

It could also be the accelerator pump is worn. Sometimes after a few years, especially if the car gets stored for months, the pumps will go bad as the rubber cups shrink or get hard. Then as it warms up it gets more pliable and starts working as correct. This happens even more these days with the ethanol in the gas. Ive had this happen to me with a rochester carb too.
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post #5 of 8 (permalink) Old Sep 10th, 14, 11:30 PM
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Re: Stumbles when not warmed up

Choke adjustment.. the engine when cold require a rich mixture and its too lean.

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post #6 of 8 (permalink) Old Sep 11th, 14, 02:15 AM
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Re: Stumbles when not warmed up

Quote:
Originally Posted by carbuff67rs View Post
It could also be the accelerator pump is worn. Sometimes after a few years, especially if the car gets stored for months, the pumps will go bad as the rubber cups shrink or get hard. Then as it warms up it gets more pliable and starts working as correct. This happens even more these days with the ethanol in the gas. Ive had this happen to me with a rochester carb too.
Very true.


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post #7 of 8 (permalink) Old Sep 11th, 14, 04:37 PM Thread Starter
Rick
 
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Re: Stumbles when not warmed up

Probably time for a rebuild on the carb. I'll give it a try and see what happens.

Thanks
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post #8 of 8 (permalink) Old Sep 11th, 14, 05:31 PM
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Re: Stumbles when not warmed up

I would just let it warm up 1st

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