Thanks for viewing-i am going to make a cam change in my 70 Challenger. Here is what i know-the engine is a 1970 440 HP-with a compression ratio of about 10 to 1 ( i don't know for sure since i myself did not have the engine bored-or choose the pistons. The 440 now has stock exhaust manifolds, a stock 4 barrel cast intake, a Holley 850 dual feed/double pumper, with a 4 speed, and 3.54 gears. Since building the engine (the car is not yet restored-so i never actually driven it) but i have decided that my cam choice is wrong for my application. The cam now in the engine is a mopar cam with 533 lift and 320 duration-i have heard good and bad stories about this particular cam. I want to go to a smaller cam/and a smaller carb. I will not be racing this car-just wanting to cruise around and have some fun. I must be getting old-because now i am concerned with gas mileage/and easy driving manners. I do however like the "bump" of a big duration cam. I may also change the intake to aluminum also. With a cam and manifold change-do you have any ideas to what the gas mileage may be.