12. Dried Out
If you’re using an old carburetor that has sat unused for a long time—such as the time it took to remove, rebuild, and reinstall the engine—it’s pretty common for the gaskets in the metering block to dry out and/or shrink, causing idle problems. If everything else seems to check out, a rebuild of the carb to replace the old gaskets will likely do the trick.
If you’re replicating a factory system or going after the style of a period dual-four-barrel induction system, you’re right in thinking it’s trickier to set up than a simple single-carb system—but not that tricky. It’s just a matter of matching your tuning inputs consistently between the carbs. Follow these tips and your dual-quad muscle car should be running crisp and clean, with great throttle response. By the way, we’re starting with the assumption that the carburetors are installed on the intake manifold and have been set up enough to be in running condition.