Mileage Question
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Mileage Question
OK...I have a 1979 F-250 4x4 with the 400 c.i. and 4 speed manual transmission. Pretty much stock except for the Edelbrock performer 400 intake and Edelbrock 1406 600 cfm 4 bbl. carb. I seem to be getting somewhere close to 8 mpg on the freeway. Does this seem excessive? I would think I should get better than that on the freeway. I am usually pretty easy on the gas pedal especially since the clutch is slipping. I also don't think my edelbrock is quite running right either. What do you guys (the ones with a similar set up) getting? I know these aren't economical vehicles, but still curious.
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It does sound a little on the low side with a 600 carb. What size tires, and gears plus
condition of the motor. I had the same thing back years ago rebuilt motor, staight up
timing small crane cam 272 dur. 524 lift. same intake with a 750 vac sec, with 38'' swampers and managed 12 mpg. never been much of a fan Edel. carbs decent out of
box but to much time changing jets and don't get me wrong the needles are easy, but
that is on the secondary side, for mileage you should not be wanting to hear the sweet
sound of a 4-barrel the Edelbrock carb makes.
condition of the motor. I had the same thing back years ago rebuilt motor, staight up
timing small crane cam 272 dur. 524 lift. same intake with a 750 vac sec, with 38'' swampers and managed 12 mpg. never been much of a fan Edel. carbs decent out of
box but to much time changing jets and don't get me wrong the needles are easy, but
that is on the secondary side, for mileage you should not be wanting to hear the sweet
sound of a 4-barrel the Edelbrock carb makes.
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"I am usually pretty easy on the gas pedal especially since the clutch is slipping"
I would tend to think a slipping clutch would not not help any with mpg's.. Also, dial in your carb using a vacuum gauge and time it so as the engine is in top tune... What RPM's are you running at at highway speeds? Again, as the previous poster asked, gears and tire size matter here as well...
I would tend to think a slipping clutch would not not help any with mpg's.. Also, dial in your carb using a vacuum gauge and time it so as the engine is in top tune... What RPM's are you running at at highway speeds? Again, as the previous poster asked, gears and tire size matter here as well...
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The condition of the motor is fair. It does have somewhere around 85k on it, but doesn't smoke and seems to be strong running. As far as gears go...I have no idea. I assume it is stock. I also believe the engine is all stock except the carb of course. The tires are Wild Cat EXT 265/75/16. Are those stock tire size? I don't have a tach (yet) so I dont know what the RPM's are. I used a vacuum gauge when I adjusted the idle mixture screws - is that what you meant? I know the clutch isn't helping, but my wife has already informed me that I don't get to tear it apart until I get her 4-runner back together!
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FWIW...my standard for the 400 is 650cfm Holley street carb, eddy intake, hooker headers, Comp DEH-255, and I can typically get that combo to pull 10-14mpg's on the highway, and never worse than 8 mpg's, depending on gears (typically between a 3.55 and 4.88), tires (33-38"), model (150/250/Bronco) and transmission (C6/NP435).
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