If when you set the idle mix screws at idle if the throttles are too far open at idle, this results in a off idle transition flat spot ( lean.) usually from a lack of idle timing.
remove both carbs and flip them over and look at the T slot exposure at idle. Pri and sec.
reset .020" ish on all 8 barrels. I bet they are un even or out of position at idle.
The at idle position of the throttles, re T slot exposure at idle is critical.
Do not set the idle using a AFR gauge, or attempt to set to any predetermined AFR at idle. Set the idle mix using a vacuum gauge for best idle quality. @ idle "best idle " is what matters, not the idle AFR. It needs what it needs.
Get this basic set up corrected first before playing with the idle air bleeds.
Very small changes in the idle air bleed have a BIG effect.
Be sure th power valves are closed at idle.
usualy blower motors with best with the timing locked out as more idle timing is better.
use a mirror to look down the carb at 2500 rpm to see if the boosters are flowing fuel, or...
What cam is in this motor?
Last edited by F-BIRD'88; 03-31-2013 at 04:16 PM.