Drill a single 38-inch hole where the strings intersect, then use a bolt to center your air-cleaner lid over the hole. Use the grout pen to draw a circle around the lid that is 1 inch greater than the diameter of the lid. The extra inch provides clearance for hood opening and closing. If Doug was content with a single four-barrel on his Rambler, the next step would be cutting this circle out of the hood using the jigsaw. Then we'd either stack a pair of filter elements to get them up into the cool air stream. Or we could make a pan-type air-cleaner base with a foam ring sealing it to the underside of the hood. This would isolate the carburetor inlet from hot engine-compartment air and take full advantage of the ram-air effect at speed. But not us . . . we're going the tunnel-ram route.