the all controversial MPG arguement

Big blocks get worse mileage for several reasons and even though 23 cubes more isn’t an end all, it is 23 more cubes to feed.

The other things about the engine come into play. The intake and exhaust track abilities (cfm amounts) has a lot has to do with it as well as the cam installed. In which most big blocks have a generous cam by compare to a small block along with valve sizes. The extra weight of the engine and trans are minuses to the equation.

The 383 can go ether way really easy. The best way to go about a decent scoot for the engine is a small cam and extraordinarily efficient intake and exhaust tracks. Excellent timing of the cam & ignition coupled with a lean at cruise carb will carry you far.

IF,.... IF! The owner can spend on drivetrain, an overdrive is well worth it. Just balance the final drive cruise rpm with your rear gears and tire size to work with your cam and you will be in great shape.