You need to update the cam if you expect much gain from the carb and headers. The stock cam wont get you much of an improvement just not enough flow to use the parts. You can add 100 hp to a stock 318 with the small heads by using bolt on parts but it will require a cam change to get there. Here's a good read for a nice mild build on a stock 318. http://www.moparmusclemagazine.com/techarticles/engine/mopp_0312_318_long_block_bolt_ons/index.html
