Join Date: Apr 2000
Location: Danville, CA USA
If the car is idling at 13:! a/f ratio it isn't lean, it is rich. Fix that problem first. Always start with optimizing the steady state conditions before moving onto the transient conditions.
If the mixture moves in the direction of lean during acceleration, then the carb is not supplying enough fuel for these conditions. If it does this a little bit in reaction to small throttle inputs, it is going to be the main jets. If it goes in the direction of lean much faster when the rate of throttle change is increased, then the accelerator pump is not supplying enough fuel. Since a dual plane intake manifold has more runner length, it has more total surface area. This will always require more accelerator pump volume to compensate for the wetting of the increased area. If you are using a carb spacer, that increases the surface area even more.
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