Fuel Line?

The thing is to do a double flare halfway. It will give the line a cone effect so it will be easier to slip the rubber fuel hose onto the metal line. Just use the tool and do the first stage of the double flare. Just dont to the second stage and it will work great. As for 5/16 line I agree to step up to 3/8 if you ever plan to race it but my sons Dart still has the original 5/16 line and runs 11.50's @ 116 with it. Ron