Hey, i know this has been adressed numerous times,but couldnt find anything and im just trying to get a few more miles outa my truck. Its a 75 F250 with a 390 motor rebuilt 5,000 miles ago. Its got a auto tranny 4x4, also a 3 inch body lift (i think) and 35inch tires with 4:10 gears. Im getting about 8-10 miles per gallon.Im moving to Duluth MN and its a pretty hilly city so i wanna increase it a bit.How could i do it,my truck is completly stock,Im looking into doing cold air intake, headersshort or long tube?) and dual exhaust. How much do you think that would help?also what about swaping gears ive heard some good and bad things about it.What should i swap them to lower or higher? i am willing to lose some power for milage.,Thanks in advance

 

8-10mpg? that's right where that truck should be, in a nearly 3 ton highboy with an automatic, FE (390), 35's and 4.10's you're just not gonna get very much better than 8-10mpg.

 

I have 1975 F250 4X4 also, rebuilt 390, edelbrock 4 barrel, 4 speed, 4:10 gears, I get 8-10 miles per gallon, also, it sucks, wish I had better news for you, but these trucks are built like a brick, they weigh a lot, and aren't built for economy, good luck

 

The best you can hope for is slight increases in mpg is the following

2 bbl instead of a 4 bbl

Or vac secondaries instead of mechanical secondaries this way you don't use more fuel until the engine really needs it.

Get an AOD transmission if you have an auto, this will reduce the crusing rpm and save fuel there.

Change the cam shaft for one made for higher gas mileage. ($$$)

Tune up the engine.

Change the rear gear ratio ( again to lower crusing rpm and save fuel )

Don't get on the gas hard when driving, keep a steady speed rather than jack rabbit starts.

Headers etc will only increase airlflow which will LEAN your mixture, you have to make it richer so going with headers, k&n air filter will not get you better gas mileage. It will only force you to go to bigger jets to get the mixture right which defeats the purpose.

Run synthetic oil in the engine

Adjust your timing for max horsepower and smoothness. ( part of tune )

Lower the truck so it's more aerodynamic ( not proven with scientific methods if this makes a huge impact on these large trucks ).

Narrow tires for less rolling resistence

Higher tire pressure also for less rolling resistence.

Lastly bigger fuel tank for longer range

Or get a geo metro ( i know they don't come in 4X4 lol )

In my case i'm just going with a bigger main tank and the aforementioned tune up and live with the 8 miles to the gallon, it is a 460 cu in after all.

 

I have to disagree with you slightly on the carb part. Going from a 4bbl to a 2 bbl will not increase your gas mileage at all. Not putting your foot in the 4bbl will increase it. When I went from 2 bbl to 4 I gained 2 mpg. Its all about how you drive it.

Also I would be happy your getting 10 mpg, these engines are not very efficient so there isn't much you can do to change that.

 

do any of you know what the mpg is on a 78 f250? no mods i think

 

yea im gettin 8-10, i guess il just deal with it. I think these trucks even with the bad gas milage are worth it.i love the style and the power these old trucks have, in my opinion id rather drive an old one than a new truck that gets 18-20 mpg.

 

Personally i don't mind the mpg's of these old trucks, granted it's horrible mileage by todays standards but back then gas was around 50 cents a gallon, these trucks are a product of their era, the few bucks i need to throw into my truck every few months for parts and/or repairs is far less than the $600 a month payment i would be making on a new 30K rig, they just don't make trucks like this any longer, it's an actual "truck" not a car/truck/suv hybrid produced to appease the soccer mom buying crowd, even chevy guys when being honest have to acknowledge the fact the 73-79 Ford trucks were the best ever to roll off the assembly line.

 

are you full time or part time 4WD?
a part time kit if you have full time 203 could get you a couple more mpg on the highway
I get 13/14 on interstate and 8/10 around town, but never try to baby it to get better
76 F-250,390 4bbl 600 Edlebrock,Performer intake, headers,dual exaust, C-6, 203 with part time kit, .410's and 35's

 

"Gas mileage?" what is this "Gas milage" of which you speak? I know not of this.

 

Another good point to remember is that if you live in a state with no emissions regulations you don't have to pay through the nose to get it to pass inspection

Plus if you insure it with classic car insurance you save the 1000 to 3500 a year you would normally spend on insurance and you can buy gas with that and still come out on top.

There are more fuel efficient trucks out there but between a monthly payment, high costs to maintain and insurance costs the little you save on fuel from buying a diesel etc won't make up for what you are spending on running costs.

That's why i chose my truck, next to nothing to insure, simple and cheap to fix,built to last, no annual inspection costs where i live, and i mainly use it for towing once in awhile.

NOTHING out there is going to tow 10,000 pounds and get phenomenal gas mileage to offset for higher running costs.

10mpg on a 20 gallon tank is roughly 200 mile range, my old 4 cyl would get 220 to 260 mile range on it's tank so if i need more range on my rig i'll put in a bigger tank.

Besides how many people actually NEED a truck this big as a daily driver?

That's why i have a smaller car for daily use and save the rig for the real work.

It's a compromise but it's one i can live with.

 

Another advantage is in may states the registration cost is based on the year of the vehicle. The older the vehicle, the lower the fee.

In Montana, where I live part of the year, there is no safety inspection and if the vehicle is 11 years or older you can get a permanent registration.

Talk about painless: no emissions inspections, no safety inspections and registration can be a one time event!

 

Excellent point

Some states like New York you are screwed with annual inspections pass or fail they charge you 35 bucks, then you have to fix the problem which god only knows how much time and labor will be spent by the mechanic trying to correct the idle mix on an old truck with an old carb.

Then it still won't pass and still cost you time and labor for it.

Luckily there are mechaincs who will just sell you the sticker for 80 bucks but insurance there just for basic liability in some cases is over 2000 and that's IF the inurance company will insure it.

So it can be a hassle

If low mileage is the least of your costs and worries, it's justified.

 

in NC, no inspection older than 35 years, only 1 year to go on the '76

 

I live in WV an I have Nationwide Insurance for now. I will shop around for better deal later but they told me $37 a month for basic liability $220 for 6 months & $440 a year for insurance vs the car I have now a 08 Chevy HHR SS $145 a month full coverage & $414 car payment for 22K for the car so compare the difference. Besides I would rather have a old truck like this that is hard on gas an has no computer sensors emissions an other crap to worry bout going out on you an leave you stuck somewere. I can always find ways to increase MPG on this truck but I cant make a new car last 35 years like my 74 truck. Besides no new vehicle will last 35 years.