250 i6 fuel economy w/o sacrificing HP

[FL71C10]

I would think the 5 speed transmission would help make up for the lower rear end gear ratio.

Originally Posted by longbed67

Get yourself a wideband and look at your #'s the 3.07 is to low of a ratio for the h- power and torque curve of a stock 250, thus you must put more foot into the throttle, thus richening the mix and killing fuel economy. I drove through the mountains with a 3.73 and a stock 250 and got 17+ all day long on my trip back from washington. If you want to keep the 3.07 you can but do a cam change, headers, clifford intake, holley 4bbl carb (get it tuned properly), and an hei ignition and you will have about 75-100 more hp and ftlbs torque and you have better fuel econ. visit www.12bolt.com, tom has a lot of info and products at very good prices that will help you out on the 250.

[longbed67]

Never thought to ask is the 15 MPG in town or highway? if your going into 5th gear on the highway with the OD .73:1 gear your going to throttle harder than if you kept it in 4th with the straight drive 1:1 gear. If it is in town... Get a proper tune on the carb jetting and ignition timing, and stay out of the throttle...