Tuning idle circuit?

[emfh76]

I have a 350 with Vortec heads, voodoo 262 cam, duel plane intake, headers, 2 1/2 inch exhaust. I recently installed an AEM wideband to help with the tuning. I have a quick fuel 650 carb and with the idle mixture screws turned out 1 full turn it still idles at 10.0. With some throttle it quickly comes up to mid 13s to 14s. I have a 4.5 power valve in it and 68 jets. I’m afraid to screw the idle mixture screws in any more. What can i do to lean out the idle circuit some?

[Jake Wade]

What does your initial timing look like?

[andyh1956]

On a Quick Fuel 650 carb, does the idle mixture screws regulate air or fuel to the idle circuit emulsion?

[Jake Wade]

Try hooking up your distributor vacuum advance to the full vacuum port on the carb. This should raise your idle rpm so you can back off the idle speed screw to your normal idle rpm. It is possible the transfer slots are exposed too much and this will close them up some.

[homemade87]

Its not a problem turn the idle scews in more than one turn . See if this helps . Check the transfer slot . Should look square at the bottom of the butterflies . If not ,close the idle screw to achieve this . The quick fuel carbs have removable idle air bleeds . If you start to get well beyond the half turn mark , air bleeds will need to be changed. This will allow more adjustment on the idle screw .

Also if a double pump carb you will have to do all 4 corners . Also has idle adjustment on the front and rear butterflies . Get as much initial timing as possible at idle . This will help also clean up the burn some .