Idle mixture adjustment advice needed
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Laughing Gas
Joined: Dec 2003
Posts: 900
Likes: 3
Idle mixture adjustment advice needed
Hello,
I just rebuilt an Edelbrock 1405 and need advice setting the idle mixture. My problem is, I'm shooting for a 14.1 to 14.7 air fuel ratio at idle using a wideband O2 sensor. I can get it in the 14.0 to 14.7 range, but it runs rough. It runs much smoother between 12.5 and 13.0 but the exhaust smells rich at that point. Thanks for any advice.
302, very mild cam, 650 rpm, 10* initial advance, engine at operating temp, made sure idle air bleeds were clear during rebuild. Comfirmed proper float level and fuel pressure of 5psi. Vac gauge fluctuates between 15" and 17" at idle.
I just rebuilt an Edelbrock 1405 and need advice setting the idle mixture. My problem is, I'm shooting for a 14.1 to 14.7 air fuel ratio at idle using a wideband O2 sensor. I can get it in the 14.0 to 14.7 range, but it runs rough. It runs much smoother between 12.5 and 13.0 but the exhaust smells rich at that point. Thanks for any advice.
302, very mild cam, 650 rpm, 10* initial advance, engine at operating temp, made sure idle air bleeds were clear during rebuild. Comfirmed proper float level and fuel pressure of 5psi. Vac gauge fluctuates between 15" and 17" at idle.
Moderator
Joined: Dec 2001
Posts: 22,436
Likes: 17
From: Louisville,Ky.
You may have to play with the initial timing and such to get closer to the 14 to 1. My 1407 on my 351W has always smelled rich at idle when running the smoothest. (Stock cam)
Mine is not as bad since I dumped the Duraspark ignition and installed a DUI HEI distributor from Performance Distributors.
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Mine is not as bad since I dumped the Duraspark ignition and installed a DUI HEI distributor from Performance Distributors.
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Postmaster
Joined: Mar 2005
Posts: 2,949
Likes: 6
From: Earth
If the vacuum fluctuates something is amiss. Check this out:
http://www.fordf150.net/howto/diagnoseengine.php
Beyond that, I'd dial in a couple of degrees more advance. An increase of 50-100 rpm idle speed might not hurt either. Since you're not running the stock cam the stock specs are out the window...
http://www.fordf150.net/howto/diagnoseengine.php
Beyond that, I'd dial in a couple of degrees more advance. An increase of 50-100 rpm idle speed might not hurt either. Since you're not running the stock cam the stock specs are out the window...
