Hey guys! I've got a 78 F-250 4x4 with a 351m. It's got a 4 inch lift and it's on 35s. It's a 4speed with 4:11 gears. I'm getting very poor mpg right now (maybe 9-10). I know this truck is never going to get amazing gas mileage, but there have got to be things I can do to improve the mpg I'm getting. I'd love to hear your guys' suggestions as to what to do Thanks! Oh, and I'm not extremely mechanically inclined, so feel free to provide extra details that you might think would be obvious haha.

 

stock tires and higher gears.

 

First Rusty
Welcome to FTE.
You've just asked the million dollar question.
You're correct you will never get great mileage but there are things you can do.
The problem with the things we would tell you to do is that you state you are not very mechanical.
A little food for thought. You have a big heavy truck that has low gears and big tires and a (I'm guessing) stock engine. The low gears can actually improve your mileage if you drive stop and go around town. Only problem there is your bigger tires are harder to turn over. However on the super slab your engine winds high and uses lots of fuel. The 35 tires here however offset/help this to a degree. The good thing is that you have a manual trans. If you had an automatic your mileage would be worse.
You're actually not doing to bad.
There are guys getting better mileage than you and there are guys doing worse.
If it's me the first thing I would do is make sure my tune up is spot on.
Then learn to drive your truck as not to use a lot of fuel. In other words stay off the loud pedal.
The next thing is to start letting your engine breath (headers, intake manifold).
Since you aren't mechanically inclined you'll need help with this stuff.
If you dive into it yourself though you will learn an awful lot.
Use the search button at the top right of the subject page to find more threads on mileage.
Welcome to the sickness.
And how about some pics of your beast.

 

Thank you so much! I absolutely love my old truck. Sadly, my knowledge is limited. But I'm very willing to learn, and everyone has to start from somewhere, right? My boyfriend and dad can help me when they're not busy, but I'd love to get good enough that I don't have to always rely on others just to do simple things.
My truck already has headers, I'm not sure on the intake manifold. I'll have to take a look! I'm pretty good at driving it, sometimes I lean on the pedal a little when I'm next to a prius, just because I can't help myself haha.
Thank you very much for your suggestions! I appreciate it alot. I know I'm that annoying new member who doesn't know anything, but I am very much interested in changing that!

Here is my rig! Don't mind the dirt ;p

 

Hah
The fact that your a girl just raised your cred to every person in this forum.
That's awesome that you love old iron.
And your truck is cool also.
Yes we all start somewhere. Just keep at it.
Tip:
Use the search button before you ask questions so that you can have a little background. Sometimes you won't be able to find what your after but at least when you ask you'll know a bit more.
Wish you a long and happy relationship with your truck and again, welcome.

 

Hate to say it but 9-10 MPG isn't bad at all for one of these, especially with big tires. You are doing pretty well!

 

Along the way of trying to understand why my engine isn't running so good now (and with an accompanying 6 - 7 MPG), I ran across some folks putting O2 sensors in to tune up the fuel/air mixture. Rather than buying one of the packaged kits, they bought a sensor and used the voltage curve and a meter to make the measurements. You can either weld a bung in the collector or I saw somebody made an exhaust clamp with a bung that only required drilling a hole. Something to consider although I don't know how much this may affect mileage.

 

I agree with everything turbo said here. ^

But otherwise, 9-10 mpg is actually pretty good. I get 5-6 in mine and mine is tuned and dialed in as well as any.

 

not to rusty, rusty.Welcome,,,my daughter wants my truck

 

Improving MPGs on a 4x is tough... more easy on a 2WD. The battle lines for every vehicle includes:

1. Engine & drivetrain efficiency... Add headers for a few HP and TQ. An intake and carb is more or less a trade-off because there is nothing free. Use synthetic lubricants to reduce parasitic driveline drag caused by thick oils and fluids. Tune it to optimize air/fuel ratios.
2. Weight! In drag racing, every 100 lbs equals a tenth in the quarter mile.
3. Rolling resistance.. heavy and wide 35s creates drag. As stated above, stock tires (hard/skinny) will reduce unsprung weight and rolling resistance because it takes more HP and torque to get things moving.
4. Aerodynamics/frontal area.. Oy.. these rigs are big bricks.. especially 4WDs with all the driveline in the air stream. If it were 2WD, I'd suggest closing up gaps and add an air dam. Btw, have you ever noticed that the grill opening is bigger than the radiator? That creates alot of dirty and trapped air.
5. Driving style is the easiest because it is free. Smooth acceleration, coasting, and anticipating stops. Look up "hypermiling" for tips on adjust your driving style.

 

Nice Truck. Ya, 9-10MPG is pretty good for that truck.

 

considering the truck and its equipment, 9-10 mpg sounds decent.......skinny 33" tires might help a little, better still if there were on alloy wheels. a really good thorough tune up. looks like Wa. state plates, does a 1978 require emissions testing? if not, i could possibly have some changes made to timing, tune etc?

 

Get a vacuum gauge and always drive in a way to maintain the highest possible manifold vacuum, it will surprise you, you would think that driving around in high gear at the lowest RPM possible would get the best MPG, not always the case, high manifold vacuum will allow the carb to atomize better, which will give the best efficiency.

I had one of those and a switch to light up when the 2nd barrels opened, crept up to 14 MPG from 10-11MPG on a 351W in a 4x4, I know, sounds crazy, but fuel was over $5 a gallon then.

I would gently pick up speed just before a hill and gradually lift off the throttle up the hill to maintain higher manifold vac, depending on the MPH I would drop it in a lower gear as the vac would stay higher there.

I tried a 600 cfm Holley and a 600 cfm Edelbrock, the Edelbrock was better.

Had the tire pressure up fairly high, clean air filter, drove with the windows up, tried everything I could, I was commuting about 100 miles a day.

Either way, light foot or heavy, we all feel the gas pump pain, I sometimes enjoy just pinning the throttle, burning rubber and telling myself it's worth it.

 

I found that the 351m, when stock, has a horrible air/fuel ratio and it makes for bad mileage. From all the research that I did I found my carb to be a major problem. The stock 2 barrel (if that is what you have) ran really rich for me and wore out the gas station. I would swap it to a 4 barrel for some more mileage. My 460 actually gets somewhat better mileage if you can imagine that. I average about 12 with 4.10 gears and 36" tires. Cheapest and easiest upgrade would be a carb IMHO.
Also welcome to FTE! I'm still newer here too but don't be afraid to ask these members anything, they won't make you feel belittled in any way and they always point people in the right direction

 

I'm very jealous of your 9-10 mpg. Quit while you're ahead! That is some nice mpg's considering you have 4.11 gears.