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Off idle stumble
Posted by: northrop n9m ()
Date: February 23, 2020 08:38PM

Hi
I have a 66 corsa 140 4 speed. I have a off idle stumble that I can't figure out. I'm not sure if it's going lean or rich. I just installed a Roger parent linkage. The carbs are adjusted and the engine is otherwise running well. Any ideas?
Thanks. Lane.

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Re: Off idle stumble
Posted by: MattNall ()
Date: February 23, 2020 08:41PM

First tell us how you set the base timing..

Then how did you "Adjust" the carbs..

MODERATOR
Sea Mountain, between Charleston Harbor and Coos Bay! SW Oregon Coast
Click HERE for My Website...Click HERE for My TechPages!
..............................110-PG.................................................Webered-Turbo

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Re: Off idle stumble
Posted by: northrop n9m ()
Date: February 24, 2020 07:18AM

I set the timing at 18 degrees with the vacuum line off and plugged. I set the carb idle speed and mixture per Bob Helts book when I installed them and then used my uni-sync to adjust the balance while it was running.
Lane

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Re: Off idle stumble
Posted by: MattNall ()
Date: February 24, 2020 07:55AM

Great..and you have a nice low idle? 650-700rpm?

Have tried backing out the Idle Mixtures another turn or two to see if that helps?

MODERATOR
Sea Mountain, between Charleston Harbor and Coos Bay! SW Oregon Coast
Click HERE for My Website...Click HERE for My TechPages!
..............................110-PG.................................................Webered-Turbo

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Re: Off idle stumble
Posted by: northrop n9m ()
Date: February 24, 2020 08:44AM

I will try the idle mixture when I get home from work.
Lane

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Re: Off idle stumble
Posted by: Seth Emerson ()
Date: February 24, 2020 10:17AM

So, after setting the timing at 18, and hooking up the vacuum advance hose, the timing at idle didn't change. Still at 18? Correct?

Seth Emerson

Check my new Performance Corvair Web site [www.perfvair.com]

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Re: Off idle stumble
Posted by: northrop n9m ()
Date: February 24, 2020 12:21PM

Hi Seth
I will check it again when I get home.
Thanks Lane

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Re: Off idle stumble
Posted by: northrop n9m ()
Date: February 25, 2020 05:10PM

Hi
I checked the timing and it's at 18 degrees and doesn't change when I reinstall the vacuum line. I also rechecked the carb balance and opened the idle screw a turn. The engine is idling at about 800 rpm.

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Re: Off idle stumble
Posted by: MattNall ()
Date: February 25, 2020 05:40PM

Is it better?


Why didn't you richen the Idle Mixtures as I suggested? 800 is still too fast..

MODERATOR
Sea Mountain, between Charleston Harbor and Coos Bay! SW Oregon Coast
Click HERE for My Website...Click HERE for My TechPages!
..............................110-PG.................................................Webered-Turbo

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Re: Off idle stumble
Posted by: PGVair ()
Date: February 25, 2020 06:09PM

Similar problem was posted here about a month ago. They found the problem was a plugged off-idle circuit in the carbs.

Wade

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Re: Off idle stumble
Posted by: PGVair ()
Date: February 25, 2020 06:12PM

Check this thread about off idle stumble.


[corvaircenter.com]

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