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Mpec2
Samba Member
Joined: May 24, 2015
Posts: 113
Location: Chicago, IL
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 Posted: Thu Jun 26, 2025 5:55 am Post subject: Idle Adjustments - Summer Heat |
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Do you find yourself needing to adjust your carbs over the course of the driving season?
Last i adjusted my carbs was in late fall last year and it ran fine through the cooler spring season but I find that during this summer heat wave (90deg +) i've got a bit of a high idle.
I've got some experience with carbs but not a ton, first full summer driving my bus on a daily basis. Considering I haven't changed anything, wondering if the engine is just getting hotter then it did when i set the carbs in the fall and in need of a readjustment.
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KTPhil 
Samba Member
Joined: April 06, 2006
Posts: 35832
Location: Conejo Valley, CA
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| Posted: Thu Jun 26, 2025 8:07 am Post subject: Re: Idle Adjustments - Summer Heat |
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Yes, I adjust the auto choke maybe three times a year. Looking for the compromise of too-high idle or dying after a couple of minutes. The "Goldilocks" position seems to change with temperature and humidity at the onset of spring and winter.
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Wildthings
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Joined: March 13, 2005
Posts: 52271
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| Posted: Thu Jun 26, 2025 8:35 am Post subject: Re: Idle Adjustments - Summer Heat |
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| Is your heat riser working and the same for you preheated air setup? They are both there to help with cold running and the preheated air is regulated by a thermostat so should supply warm air for longer periods of time during the cooler months. |
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Mpec2
Samba Member
Joined: May 24, 2015
Posts: 113
Location: Chicago, IL
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| Posted: Thu Jun 26, 2025 1:22 pm Post subject: Re: Idle Adjustments - Summer Heat |
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I'm running dual weber 34 ICT's so no heat risers or preheat set up.
I do have a heat spacer at the manifolds, but my understanding is that helps mostly more with vapor lock and boiling the gas in the bowls.
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Wildthings
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Joined: March 13, 2005
Posts: 52271
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| Posted: Thu Jun 26, 2025 1:38 pm Post subject: Re: Idle Adjustments - Summer Heat |
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| Mpec2 wrote: |
I'm running dual weber 34 ICT's so no heat risers or preheat set up.
I do have a heat spacer at the manifolds, but my understanding is that helps mostly more with vapor lock and boiling the gas in the bowls. |
Blocking heat from reaching the manifolds along with no preheated intake air is likely why you have your carbs adjusted to provide extra idle air flow. Probably no ready solution other than to adjust your carbs as needed spring and fall. |
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kreemoweet
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Joined: March 13, 2008
Posts: 4087
Location: Seattle, WA
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| Posted: Thu Jun 26, 2025 5:12 pm Post subject: Re: Idle Adjustments - Summer Heat |
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Gasoline is also reformulated with the changing seasons, and so could very well affect the carb idle settings.
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SGKent
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Joined: October 30, 2007
Posts: 42381
Location: at the beach
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| Posted: Thu Jun 26, 2025 11:35 pm Post subject: Re: Idle Adjustments - Summer Heat |
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put a few drops of oil on the distributor wick. The hot temps may be causing the weights to hang and changing the timing. Also check all your hoses to be sure none have cracked or fallen off. Make sure the vacuum advance still holds pressure. Check the brake booster for vacuum leakage too. Any of these items could cause the idle to increase.
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