Acheiving 20mpg
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Senior User
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From: eugene
Acheiving 20mpg
What would you have to do to achieve 20mpg from a 390?
I know I have read some things including 32mpg on a stang i'm sure all of u have read the article http://mustangandfords.com/techarticles/5228/
What parts would you have to use, probably like tall gears in the rear, some headers would help. What kind of carb. 2v or 4v.? would it help to have a short bed?
I'm sure it would be a lot easier on a 302 or a straight 6. just wondering about the 390 for now cuz i'm always wanting a challenge.
I know I have read some things including 32mpg on a stang i'm sure all of u have read the article http://mustangandfords.com/techarticles/5228/
What parts would you have to use, probably like tall gears in the rear, some headers would help. What kind of carb. 2v or 4v.? would it help to have a short bed?
I'm sure it would be a lot easier on a 302 or a straight 6. just wondering about the 390 for now cuz i'm always wanting a challenge.
Elder User
Joined: Mar 2004
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From: SOUTH CAROLINA
drive down hill.......... 
really, reduce drag, a bed cover, a light foot on a perfectly tuned engine and no city driving. tires, size and tread style are important here. induction and exhaust that are optimal for your engine setup. probably a small 4v carb and intake would do better than a 2v, headers and a free flowing exhaust. gears that are purpose of the type of driving (city or highway) alot factors in. overdrive would probably help. good luck
really, reduce drag, a bed cover, a light foot on a perfectly tuned engine and no city driving. tires, size and tread style are important here. induction and exhaust that are optimal for your engine setup. probably a small 4v carb and intake would do better than a 2v, headers and a free flowing exhaust. gears that are purpose of the type of driving (city or highway) alot factors in. overdrive would probably help. good luck
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From: nevada
4cammer has it right, you will need more than luck tho. You could also jet the carb way down, but will prob burn some valves in the process. Play with the timing, and duck in behind a big semi on the highway.
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From: "Islander"
That article "Ed predicts 32 mpg" with a 600 HP and 600#TQ 390 motor in a Mustang. A 4,500 pound brick (truck) might get that mileage if jetted super lean, 2:1 axle and a constant speed of 25 mph. JMO's.
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From: eugene
Originally Posted by hog caller
while we're an the subject how about 20mpg with a 300 six automatic and 3:73's. Is that possible?
17 is achievable right?
I'm being serious here... I want to know what the best setup would be to get best mpg...
I know that there are fuel injection systems.... that probably help... the gears would help... A c6 probably wouldnt help...... cam helps... headers help, exhaust, heads.... etc..... but what kind is what im trying to get at.
Setup and driving conditions are different.. I'm talking about setup not conditions.
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From: eugene
A long time ago I saw a web site that had 67-72 fiberglass front clips . the whole thing would just flip up toward the front....
That would reduce a lot of weight and probably improve mpg
That would reduce a lot of weight and probably improve mpg
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Elder User
Joined: Jul 2005
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From: North Texas
Errr, guys, don't forget that jetting lean, especially lean enough to burn valves, will lose power and cause drivability problems. That will make you tip in more throttle. A very slightly lean cruise is good economy wise, but any more than that will actually hurt fuel economy.
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From: springfield,or
well, i'm trying to get mileage out of my 69 f100, 2wd ,300I6, manual and no powersteering with 3.70 gears. so far after i bought it it had 9000 miles on engine it got about 17.5 average and 20 best ever in the summer. But in the winter now the best i got is 16, average more like 13 to 14 , even after putting on a accel coil to help with cold starts and to help the engine handle the cold<12 was worst i got>. Seems my carburetor has some adjustment needed, i guess. Becayse it don't handle cold very well, it wants to hesitate and die when you accelerate.
The motor in the truck was originally a 240, but the owner switched to a 300 from a early to mid eightes motor with rv cam. He took all the 240 accessories and put it on the 300, so i'm wondering if there is a difference in the carburetor and distribitor at all. I would like to have somebody help me with this.
Hope this helps P.S. i see joe your from eugene i'm over here in springfield, small world
The motor in the truck was originally a 240, but the owner switched to a 300 from a early to mid eightes motor with rv cam. He took all the 240 accessories and put it on the 300, so i'm wondering if there is a difference in the carburetor and distribitor at all. I would like to have somebody help me with this.
Hope this helps P.S. i see joe your from eugene i'm over here in springfield, small world
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From: springfield,or
Joe, looks like you have a very nice rig, to nice to sell i say! i have a 390 in a f250 also i say without the speedometer to tell me how well it does. I guess about 12 to 14 a gallon if i keep my foot out of it. it has a 4brl holley carb my jets at 64 front and 66 rear with i think 1 step down from standard spring, stock exhaust system and the entire truck is old. exhaust leaks i got em, you get the picture. i even did a crappy paint job on it, but hey i tried
i'm doing the best of anyone i know in gas mileage.
i'm doing the best of anyone i know in gas mileage.
Fleet Owner
Joined: Jun 1999
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From: Creedmoor, North Carolina
Originally Posted by joegeoghegan317
What would you have to do to achieve 20mpg from a 390?
I know I have read some things including 32mpg on a stang i'm sure all of u have read the article http://mustangandfords.com/techarticles/5228/
What parts would you have to use, probably like tall gears in the rear, some headers would help. What kind of carb. 2v or 4v.? would it help to have a short bed?
I'm sure it would be a lot easier on a 302 or a straight 6. just wondering about the 390 for now cuz i'm always wanting a challenge.
I know I have read some things including 32mpg on a stang i'm sure all of u have read the article http://mustangandfords.com/techarticles/5228/
What parts would you have to use, probably like tall gears in the rear, some headers would help. What kind of carb. 2v or 4v.? would it help to have a short bed?
I'm sure it would be a lot easier on a 302 or a straight 6. just wondering about the 390 for now cuz i'm always wanting a challenge.
I'm taking my truck out on a 300 mile run today, I am hoping to get 14 if I can stay out of the carb. Drove it for the first time yesterday in a couple o weeks. Man what a testostorone rush. Arg Arg Arg.
John
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Joined: May 2005
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If you really try, you might get close.It may take the kind of tuning than racers do to achieve it, meaning alot of tweaking and changing. I was driving my 68 Ranger, 360, AT,PS on the highway at 75-85 mph and was getting 14mpg. Keep in mind, this was as I bought it. It had been sitting for awhile and I didn't have time to go through it. No tune up, no service other than an oil change. Good luck and let us know how you do. 
Posting Guru
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From: Madison, SD
One other thing, the older Ford pickups are about as aerodynamic as a brick. That plus the fact that they set up in the air too high and the air going under the truck has to work it's way around all the suspension peices hanging down there in the wind. As someone else said, a bed cover would also help some. I would imagine with all the right peices and a perfect tune in ideal conditions cruising sedately down the highway 20 mpg may be doable. Perhaps a conversion to a TBI injection unit??? Doubt if 20 mpg could be maintained on a daily driver with city driving and such. JMO
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From: washington
The best way I've found to do it is replace the speedo driven gear with one or two teeth less. Added bonus is fewer tickets, cleaner oil between changes.
Just can't help being a wise guy.
Realy though what I do is calculate the difference of mpg,insurance rate,payments of a new truck and make a happy face with that.
Just installing a better ignition system and economising the fuel system can take a while to pay itself back. I'm not against a challenge but you're saving a lot just driving that old truck.
One last thing, how about a quiet exhaust? I know I like to listen to her wrap up a few R's.
Just can't help being a wise guy.
Realy though what I do is calculate the difference of mpg,insurance rate,payments of a new truck and make a happy face with that.
Just installing a better ignition system and economising the fuel system can take a while to pay itself back. I'm not against a challenge but you're saving a lot just driving that old truck.
One last thing, how about a quiet exhaust? I know I like to listen to her wrap up a few R's.