plug fouling

I have a 318 thats fouling plugs like crazy...this has just started and i am now on my 3rd set of plugs in 2 months.....its a pretty much stock 318.. has headers, mild comp cam,, holley 650 with weiland intake.... the ignition is stock... its the original motor in my 1974 Dart...... any ideas as to why i am going through plugs???? ... thanks for the help..