Originally Posted by crazzywolfie
i was wondering if it worth my time to clean up some of the rough spots? already started cleaning some of it up but i am not really getting far quick. hoping to get as much torque out of the 318 magnum as i can.
Polishing will do a little bit to reduce an amount of resistance, however you aren't going to notice any changes. You will have better results by just switching over from a paper element air filter to a synthetic fiber based one. If you really want to feel a change I would get rid of that manifold and go with a manifold that has a lower volume like the ones by Hughes. The stock manifold is mostly for torque, one with a lower volume is focused around HP, so it's your choice. Also the difference between a single plan and dual is very small in the case of stock heads and valves. I would stick with a single plane with this engine because of the layout or profile of the crankshaft and camshaft, during a 720 degree cam rotation two cylinders on one side of the engine are filling so it is important that those cylinders can get enough air so that is why I favor single plane with this engine, if you noticed the performance manifold by Chrysler for these are single plane. But again with a mostly stock engine it won't really make a giantic difference. But it will be noticeable!