MPG's
Posting Guru
Joined: Feb 2013
Posts: 1,323
Likes: 3
From: Sunny Florida
18 mpg in the 77' long bed 2wd AT
15 mpg in the 78' short bed 2wd AT
10 mpg in the 73' short bed 2wd AT.
Used to have a 79' F150 4x4 short bed with a cammed 429 CJ, AT and 38.5 Ground Hawgs... Better measured in GPM... Gallons per mile!
15 mpg in the 78' short bed 2wd AT
10 mpg in the 73' short bed 2wd AT.
Used to have a 79' F150 4x4 short bed with a cammed 429 CJ, AT and 38.5 Ground Hawgs... Better measured in GPM... Gallons per mile!
New User
Joined: May 2015
Posts: 17
Likes: 0
74 F100 390 two barrel Motorcraft, stock except for dual exhaust, c6 auto 3.50 rear gears, 235/75r15 tires, around 2750 rpms at 65 mph. So far getting between 12 and 14 mpg highway.
Thinking about swapping to 2.75 rear gear... but will it help the mileage? I would like to get over 15 mpg and be able to drive 70 mpg without winding it out so much...
Thinking about swapping to 2.75 rear gear... but will it help the mileage? I would like to get over 15 mpg and be able to drive 70 mpg without winding it out so much...
I suggest a E4oD transmission out of a 92 to 96 f150 this is the 4spd equivalent of your C6. It is electronically controlled and there are stand alone controllers available at a reasonable price.
Your gear ratio at 70 mph with a E4oD swap with 3.50 gear is 2024. depending on where you live this would be a little low for my liking cause I live in mountainous region. I would deepen the gears to 3.73 or 3.92 and still be between 2157 and 2267 rpm at 70 mph.
Another thing is aerodynamics, there is not that can be done about this other then lowering and some sort of bed cover like a shell or tonneau would help slightly.
Elder User
Joined: Jan 2003
Posts: 759
Likes: 0
From: North Dakota
Thanks for the info Grimm13... I have only driven mine about 300 miles so far so I am not accustomed to much, ha ha. Right now I have sandbags so it doesn't spin out so much on the gravel, so a little less go on the low end would be OK.
And I may be able to get the gears swapped for around $300 to $450, where the e4od and controller would be much higher investment.
Thanks again, I will be thinking and researching...
And I may be able to get the gears swapped for around $300 to $450, where the e4od and controller would be much higher investment.
Thanks again, I will be thinking and researching...
New User
Joined: May 2015
Posts: 17
Likes: 0
Thanks for the info Grimm13... I have only driven mine about 300 miles so far so I am not accustomed to much, ha ha. Right now I have sandbags so it doesn't spin out so much on the gravel, so a little less go on the low end would be OK.
And I may be able to get the gears swapped for around $300 to $450, where the e4od and controller would be much higher investment.
Thanks again, I will be thinking and researching...
And I may be able to get the gears swapped for around $300 to $450, where the e4od and controller would be much higher investment.
Thanks again, I will be thinking and researching...
Elder User
Joined: Jan 2003
Posts: 759
Likes: 0
From: North Dakota
Most of my trips will be 45 mph on 8 miles of gravel and 55 mph on 6 miles of pavement to town... the "big" city is a other 25 miles with a 65 mph limit. Probably only get there once a month with the pickup...
Might be best to stay with what the factory did!
New User
Joined: May 2015
Posts: 17
Likes: 0
In researching I have also read that the FE engines like to rev a bit and that 3000 rpm doesn't really hurt them... and I remember reading that if your cruising rpm is close to stall speed of converter that you will end up with too much slippage too.
Most of my trips will be 45 mph on 8 miles of gravel and 55 mph on 6 miles of pavement to town... the "big" city is a other 25 miles with a 65 mph limit. Probably only get there once a month with the pickup...
Might be best to stay with what the factory did!
Most of my trips will be 45 mph on 8 miles of gravel and 55 mph on 6 miles of pavement to town... the "big" city is a other 25 miles with a 65 mph limit. Probably only get there once a month with the pickup...
Might be best to stay with what the factory did!
New User
Joined: May 2015
Posts: 17
Likes: 0
apparently the 1978 to 1979 frame motor mounts for a 351m & 400 will work with a 351W, so you may be able to get a mid 90's F150 351W with a ZF5 and get fuel injection at the same time.
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Elder User
Joined: Jan 2003
Posts: 759
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From: North Dakota
I was thinking a 2.3 Ecoboost and six speed out of the new Mustang... or swap in a 4bt Cummins to improve mileage... as long as I am dreaming!
New User
Joined: May 2015
Posts: 17
Likes: 0
The 4BT with a 5R100 transmission out of a 6.0l ford superduty, a NP271 manual transfer case and 3.92 gears is the set up I am working towards in mine. The ratio will be 1859 rpm at 65 mph with a 33" tall tire which is just about perfect, in the torque band with enough to get you higher if you choose. Personally I go a little slower, its a little quieter and I plan ahead.
Fleet Mechanic
Joined: May 2012
Posts: 1,724
Likes: 1
From: peru kansas
Steven@nd Fe's work great with 2.75 gears i avg'd 16 mpg for an entire year of daily driving with a healthy Fe (pnp heads and aluminum intake, headers, and 4bbl 650 holley), 435np, 265-75-16's and she wasn't a slouch i hauled firewood all the time with it essentially 3rd becomes 4th and 4th becomes overdrive...
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