Do not jump to putting an after market 4 barrel intake on your 318 2 barrel engine. Will bolt up and work but not as good as it should. The 318 heads have smaller intake ports and most 318/340/360 aftermarket intakes have bigger ports. This cause the intake air to be disrupted when going into the head. You can do a lot of grinding to port the heads to match the intake. Easy way is to find a stock 4 barrel intake that already matches up to the heads. I have a 318 in my 72 Satellite, that I found a 1981 Dodge Diplomat 4 barrel 318. Got the intake, and it matches up great. Put on a 390 CFM holley and runs great. Getting about 20-21 MPG on the road.