20. To match the Performer 390 intake manifold, and the stock 360 engine beneath it, we chose an Edelbrock Thunder AVS off-road carb that flows 650 cubic feet per minute (CFM). The Thunder AVS off-road carb has a spring-loaded metering needles and seats for superior fuel control in rough off-road terrain. We ordered the manual choke model to keep everything dirt-simple. There are three vacuum ports up front, and a large port out back. You'll need to use the provided plugs to block off the ports you don't use. The carburetor comes with a tuning manual, and you can also call Edelbrock's Tech Line (800) 416-8628 for further assistance.