gearing vs mpg

MOhorsePAR said
Just remember, depending on the specs of the cam your running, your engine may now not be operate efficiently at the new lower RPM. Turning a bigger cam motor at a lower than optimum RPM means it's running at the very bottom of it's torque curve and requires more fuel to make power. Other than the possibility of a little less engine wear and a reduction in ambient noise, the saving in fuel may not be worth the hassle of the gear change. Your call. 8)

Steve / MOhorsePAR

That's a very good point. If your cam is too big to make torque at low cruising RPM's then you won't see much of an improvement by cruising at those lower speeds.

Vacuum gauge is also a great idea. In fact I have an AutoMeter 2-5/8" 0-30 in./Hg vacuum gauge in my car and it is very interesting to watch. You can really see the difference it makes in accelerating slowly and steadily vs. hammering the gas.