Classic Mustangs (Tech)Technical discussions about the Mustangs of yester-year.
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well what has been done meaning how many modifications, and the carburator will determine how much gas is put into the engine basically. The bigger the carb, the more gas, and usually the more power (don't go overboard on the carb tho).
I have a 351w but havn't been able to determine my mpg yet. Wouldn't be suprised if it was 12.
Hahaha...do you really want to know the answer to that question? Mine, with a stock 4300 4v gets an average of 12 mpg, which is mostly city/country driving. If I were to drive on the highway I would expect it to get much better.
1969 Mach 1 - 351W-4V, FMX auto (original 4-speed)
Fuel economy, is more than just carb and engine mods. A poorly tuned carb will affect mileage. You also have to consider transmission, gear ratio and tire diameter. My 351w has a roller cam, Holly Systemaxx II heads, 650 Speed Demon carb, T5, 3.50 gears, and 25" tall tires. The combo on the highway gets me almost 19 mpg in 5th gear.
My Cuda has a 318, holley 450 cfm carb, T5, 4.11 gears, 25" tall tires, 5th gear on the highway, 18 mpg.
My Falcon, had a 260 and 2 speed ford-o-matic, 2v carb, 3.0 gears, 25" tall tires, got me 13 mpg on the highway. Swapped in a roller 302, holley 450, T5, and 26" tall tires. 5th gear on the highway gets me 21mpg.
289, paxton 6lbs boost, 650 bouble pumper, 4 speed toploader, 3.55 gears, 25" all tires, =8mpg on the highway.
I calibrate my speedo after all my car mods that affect the odometer. If you change the rear end gears to highway gears you can gain a few more mpg. Taller tires will help, and overdrive.
My newest combo, 408, Vortech 15lbs boost,750 blow through Demon, Viper 6 speed, 3.70 gears and 25" tall tires. 6th gear @ 2000 rpm=80mph. I will be happy if I can get 14 mpg on the highway.
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