72 cutlass 600 carb. If I put a nice intake manifold and headers 2 1/2 pipes and drive it like gramps will it improve gas mileage?

 

You can always improve gas mileage by driving like gramps, but doubtful enough to pay for a different and not necessarily better manifold. Also, headers and 2 1/2 exhaust usually won't do much if you drive like gramps. They are designed to improve performance and power. You need to decide if you want more power or more fuel mileage. If you want more mileage, just driving like gramps is the most cost effective way with no mods.

 

Improving the exhaust flow will make the engine more efficient. A more efficient engine will use less fuel to achieve the same power level, or will make more power with the same amount of fuel. So it can help improve fuel efficiency (and increase MPG), but those gains can be easily erased by putting your foot down on the gas pedal.

So as stated above, the easiest way to improve mileage is to drive with a very light right foot.

 

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Yes, but...

If you want to use less gas, then using smaller intake and exhaust tubing will get you there with the least loss of performance by increasing velocity and scavenging at the engine speeds that you are using when driving conservatively.

Think Edelbrock SP2P.

- Eric