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#1 |
Senior Member
Join Date: Mar 2003
Location: St robert Mo
Posts: 2,001
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idle mixture
When adjusting the idle mixture screws is it best to take the vaccum reading from carb or intake? Just wondering if it matters.
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1968 c10 lowered 3" 4" 355/Th400 built by Hatfield racing in joplin MO |
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#2 |
Senior Member
![]() Join Date: Aug 2004
Location: Centennial, CO
Posts: 2,956
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Re: idle mixture
Whatever gives you full manifold vacuum. I think it's easiest to go off the brake booster line. Some of the carb lines may be ported vacuum for timing advance, EGR or whatever.
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ClusterTruck: 68 C10 Bought in 89, wrecked in 03. Slow low $ rebuild started '17. 6.0 & TKO http://67-72chevytrucks.com/vboard/s...d.php?t=788602 93 K1500 Short Step, 350, NV4500, EBL flash ECU. Vortec heads & roller cam someday... 05 Jeep Wrangler Unlimited. 3” lift & 6-speed 02 E320 the insurance total “free car” 13 Tahoe LTZ |
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#3 |
Senior Member
Join Date: Mar 2003
Location: St robert Mo
Posts: 2,001
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Re: idle mixture
ya I normal use the full vaccum off the carb but just wondering if it would be better off the rear intake port.
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1968 c10 lowered 3" 4" 355/Th400 built by Hatfield racing in joplin MO |
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#4 |
A little east of nowhere
Join Date: Feb 2006
Location: LaBroquerie,Manitoba Canada
Posts: 168
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Re: idle mixture
The rear intake port or anywhere on the manifold below the throttle blades will give you a true vacuum reading.
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#5 |
Senior Member
Join Date: Dec 2004
Location: Southern Pines NC
Posts: 3,853
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Re: idle mixture
Make sure your timing is set right and points dwell too, before you try to adjust the idle mixture. You will have to reset the idle speed.
You can also set the idle mixture by going for the highest idle speed when turning the screws |
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#6 |
Senior Member
Join Date: Mar 2003
Location: St robert Mo
Posts: 2,001
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Re: idle mixture
No points qksilver HEI. I find it is easier to set with a vaccum gauge. I think I will just pull the hose going to the tranny on the manifold and hook up there.
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1968 c10 lowered 3" 4" 355/Th400 built by Hatfield racing in joplin MO |
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#7 | |
Registered User
Join Date: Oct 2005
Location: N Texas
Posts: 727
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Re: idle mixture
Quote:
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67 C10 Shortbed 327 05 F150 4x4 NO APPOLOGIES ![]() 02 Xpress X19 02 Yamaha VMax 150 www.xpressboats.com Nothing says 'poor craftmanship' like wrinkles in your duct tape |
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