What could I do to my 1971 f250 4x4 with 4.10 gears to improve fuel mileage ?

 

Just to list a few. Install a over/drive trans, drive slower,add headers with dual 2.5 pipes, Hotter ign. system, K&N air filter, run a fan clutch,
weight almost 6k with Big tires on them. 8-11 mph for the normal trucks Add O/d 1-2 more mpg

Orich

 

What are you getting now?

Best bang for the buck would almost have to be a good tune up, to include a new distributor, and dial in as much ignition advance as the engine will tolerate without pinging or pre-detonation. Make sure your vacuum advance diaphragm is in good condition and connected. It alone provides about a 15% improvement in MPG compared to running without it. Not much in actual gallon terms maybe but every bit helps. I'd rebuild the carburetor, and take a close look at your plugs. You can probably use a bit smaller jet size if you are careful. Jet down till you get lean surge or bucking at steady cruise on highway, and then go back up a size or two. Keep in mind you need some leeway to account for temperature and altitude (density) changes.

Remember your truck is aerodynamically a brick, there's not much to be done about that.

 

Swap the 4.10 gears for 3.54s. 235/85 tires And what was said above.

 

Leave it parked, you can spend hundreds of bucks on the stuff mentioned above and you might pick up 1 mpg if you are lucky.

Just suck it up, drive it slower and be happy.


John

 

I changed and adapted a 1974 Buick 455 Quadrajet to my 390 with 35 inch tires, 4.10, C6, headers ect.. and now average 13 from 8 mpg.. I have a post somewhere on here from a few years back on it.. As they claim in advertising, Your results my vary..

 

I agree but we don't know where he's at right now mileage wise. Maybe he's only getting half of the potential range possible? Who knows this is why I asked.

Any engine in poor state of tune will dump raw fuel into the cylinders and wash out rings, foul plugs, dilute the oil, spew excessive pollution, trash the cat converter, fail smog, waste money, etc etc. It pays to keep a motor tuned up for reasons other than fuel mileage. Depending where it's at now a few tweaks could make a big difference help keep the engine reliable.

 

Don't drive it , LOL
Just kidding but the Fe is a pig no way around it . at best I have heard 13-14 MPG

 

LOL Jowilker you beat me to it

 

Smaller jets are not always the answer. On a 74 F250 4x4 I had new, Ford's solution to poor mileage was 2 sizes larger jets and advance the timing. Doubt if it made much difference though.
The best thing you can do on these trucks is slow down. The difference in fuel consumption between 65 and 55 is considerable.
With stock sized tires you are running about 2800 rpm at 65. You could go to 33s and drop that by a couple hundred. But tall skinny tires are hard to find and the talller the fatter which is counter productive to fuel economy. Unless you could find a set of the rare 19.5 wheels that were optional in the late 50s to mid 60s on 4x4s.

 

Right now I am getting 8-9 mpg depending on where I am

 

What type of carb & size 2brl or 4brl holly of autolite. his is a starting point.
Orich

 

It's a 4brl holly I believe

 

Pretty typical of this engine....

 

Especially in a 4wd 250.

OP, you might be able to get up to around 12 with everything we've mentioned, but my 2wd 100 with overdrive only averages 13.