390
Post Fiend
Joined: Jan 2003
Posts: 8,600
Likes: 4
From: Iowa
It all depends on the state of the engine and the tuning. Old worn out engine = bad gas mileage. Incorrect tuning = bad gas mileage. It goes the other way too. Engine with good, consistant compression in all cylinders = good mileage. Correct timing and fuel mixture = good mileage.
Could be anywhere from 5 to 15mpg.
Could be anywhere from 5 to 15mpg.
Laughing Gas
Joined: Jan 2002
Posts: 1,008
Likes: 1
From: Tucson
Bear in mind that rusty's "good mileage" is a relative concept. You really must add "for an FE!" I love my FEs but that love is getting more painful as we top $3 per gallon. Anyhow, I get about 8 mpg from my 390 that I drive hard and over 12 on my 360 that I poke along in.
jor
jor
Post Fiend
Joined: Jan 2003
Posts: 8,600
Likes: 4
From: Iowa
Gas mileage is indeed a relative concept. I got 15mpg with my 390, 17 on one particular trip. What's interesting is dad's new 2006 F150 with the 5.4L averages 15.5mpg, and my engine is making a lot more power. 
FTE Leadership Emeritus
Joined: Jul 2002
Posts: 42,561
Likes: 423
From: Long Island USA
Originally Posted by rusty70f100
Gas mileage is indeed a relative concept. I got 15mpg with my 390, 17 on one particular trip. What's interesting is dad's new 2006 F150 with the 5.4L averages 15.5mpg, and my engine is making a lot more power.
HOWEVER - that's in a 5500 lbs Highboy.
The V10 in my Superduty get's at least 15 on the highway, puts out more torque and the whole thing weighs at least 6500lbs.
Big truck, big gas bill. PERIOD.
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Posting Guru
Joined: Nov 2004
Posts: 1,111
Likes: 0
From: Turlock CA
I used to own a 68 F250 with a 390 C6 don't remember what the rearend had for gears, it would get about 13 to 14 mpg and that was even when I towed my fith wheel.
I now own a 65 with a 352 four speed granny tranny with 3.00 rear gears. Before the tunning and the gear change it used to get tops 9 mpg. Now if I keep it at 65 and watch the vacuum gauge I can get as high as 17 (rare) I have been averaging 15.5 mpg at 70 mph. I tow a small 14' boat to the lake and it doesn't change the mpg.
I will have to agree that it is in a good tune and a soft foot. Heavy foot cost you $$$.
jd
I now own a 65 with a 352 four speed granny tranny with 3.00 rear gears. Before the tunning and the gear change it used to get tops 9 mpg. Now if I keep it at 65 and watch the vacuum gauge I can get as high as 17 (rare) I have been averaging 15.5 mpg at 70 mph. I tow a small 14' boat to the lake and it doesn't change the mpg.
I will have to agree that it is in a good tune and a soft foot. Heavy foot cost you $$$.
jd
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New User
Joined: Feb 2006
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Thanks guys for your information. I've been busy. So hopefully in the future I can get at least 15 mpg. And as far as the motor I don't know how it exactly is, but it seems to be a good motor. That's just how I bought the pickup and was told there was nothing wrong with the motor. So my point is, Idon't know what kind of cam and compression it has. Or is there a way to find all that out?
Ford Parts Specialist
Joined: Nov 2006
Posts: 88,826
Likes: 787
From: Simi Valley, CA
Originally Posted by jd_sylvia
I used to own a 68 F250 with a 390 C6 don't remember what the rearend had for gears, it would get about 13 to 14 mpg and that was even when I towed my fith wheel.
I now own a 65 with a 352 four speed granny tranny with 3.00 rear gears. Before the tunning and the gear change it used to get tops 9 mpg. Now if I keep it at 65 and watch the vacuum gauge I can get as high as 17 (rare) I have been averaging 15.5 mpg at 70 mph. I tow a small 14' boat to the lake and it doesn't change the mpg.
I will have to agree that it is in a good tune and a soft foot. Heavy foot cost you $$$.
jd
I now own a 65 with a 352 four speed granny tranny with 3.00 rear gears. Before the tunning and the gear change it used to get tops 9 mpg. Now if I keep it at 65 and watch the vacuum gauge I can get as high as 17 (rare) I have been averaging 15.5 mpg at 70 mph. I tow a small 14' boat to the lake and it doesn't change the mpg.
I will have to agree that it is in a good tune and a soft foot. Heavy foot cost you $$$.
jd
In town mileage has always been around 10-12.
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