I've got a '77 F150 that gets about 11mpg. Can I get better fuel mileage without losing power or spending thousands$$$? I drive very gently, most cars pull away from me after every stop, I cruise at the speed limit to 4mph over. I'm open to any suggestions.

Specs:
modified 400, freshly rebuilt, RV cam, 600cfm carb, performer intake, dual exhaust, no headers.
C6 automatic
2.75 rear gear, 2wd
regular cab, long bed, small truck tool box.

 

Install a vacuum gage and watch it while you drive. Otherwise keep it tuned up, maybe try a dyno tune with an eye towards economy.

A stock type cam will give better economy. A C6 can be improved with internal bearing mods but now we are talking $$. A standard transmission is also more efficient.

 

I really don't think you are going to get much better than that. Eveything sounds real nice the only thing I could possibly suggest to you would be to buy the Tornado! it sits inside the the air cleaner as easy as changing the air filter. And you can have one ordered at almost any parts store for $50-60. and if anything else, you could try what I did on my 400m take off the 4-barrel and add a 2-barrel. right know I'm running a 500cfm holly 2-barrel on my 79 4x4 f150 supercab longbed (very heavy) and I average around12 -13 mpg.

 

Torque1st: Install a vacuum gage and watch it while you drive.
Can do.

Torque1st: maybe try a dyno tune with an eye towards economy.
Also can do for about $55. Probably also the cheapest way to get an accurate air fuel ratio. Always wanted to know what it makes anyway.

Torque1st: A standard transmission is also more efficient.
What's the cheapest I can get a big block manual(non-OD if cheaper, 2.75 gears remember?), bell housing, clutch, pressure plate, flywheel, clutch pedal setup, etc?

modified79: the only thing I could possibly suggest to you would be to buy the Tornado!
The squirrel cage looking device? I know the EPA doesn't think they work. Did you find differently?

modified79: right know I'm running a 500cfm holly 2-barrel on my 79 4x4 f150 supercab longbed (very heavy) and I average around12 -13 mpg.
I've got an autolite 2100 2V aroud here somewhere... used a couple years back. I could try it out.

 

I had a 79 f150 super cab with the 351M 2bbl. and the same gear ratio you are running and I got about the same. You might consider an electric fan from flex-a-lite. I swapped one in on my 76 390 and gained 1-2 mpg. However, the fan cost something like $200 so it would take a while to pay for itself. Headers can also help a bit on mileage and a lot on power, but they can be costly and are painful to install.

 

A very inexpensive upgrade is to change out the camshaft timing gears (and new chain, of course) for a '69 429/460.
This will undo the built-in cam retarded timing necessary for pollution control, and will restore power.
This is an easy and inexpensive change; it only requires you remove the front timing cover. You do not need to tear the entire engine down.

By the way, I get just under 15 MPG with my 460 in my '66 F-100, with these gears and with a 2.75 rear end.

 

Even though I have a clutch fan? If so have a spare electric fan, just need a thermostatic switch then I can try that.

I have a "straight up" timing gear already. I've heard that the 460's have better heads and get better mileage despite the extra cubes.

 

Another thing is to get rid of as much weight as possible. Perhaps chuck tools, spare tire, maybe tailgate. I read somewhere you can gain a 1/2 mpg for every 250 lbs you ditch.

 

You can do all the upgrades and improvements you want but the “Law of Physics” has already decided the best you can do with what you have. So, I think what you are asking is how much it will cost for an unknown MPG improvement………….

My guess is that to make any real difference the payback is going to be so great that if you must have good, bottom line MP$ (no mistake), you cant drive enough miles to make it worth while and you would be better off giving the old girl a good tune, buy a 4cyl, 2wd.......... then drive your REAL truck when necessary.

Don’t get me wrong, I love my old 78, 460, 4WD and drive it every day (so far 500K)........ but....... for that I pay the price.

Now this is only my third time around with "unbelivable gas prices" however I have learned; the magnets dont work and gas prices dont go down.


My opinion cost you nothing and its worth less than that.……………….OUT

 

I dont think there is a whole lot you can do... Mine gets 9 mpg, but its a 4wd. It is consistent though, i drove it for a couple tanks real easy and it only got about 3/4 a mile better. I can pull a lawn care trailer (the ones with the big expanded metal gate on it that acts like a sail) and its gets within 1 mile per gallon of usual. The thing about most products that improve mileage are so expensive they take a while to pay for themselves from the fuel savings. The best thing to do is drive less. I used to make about 2 trips to town a day ( 3 miles each way) but now i make damn sure that ive done everything in town i will need to do for that day so i wont have to come back.

 

Very true. I'm looking at it with cost in mind. I want a maximum of a 1 year payoff. From what I can tell 15mpg is about the best anyone can get with a F150 & 400. The yearly savings of 11-15mpg is about $700. So if I can find a definite pattern in the couple of guys with more economical 400s I might be willing to invest up to $700. So far the only possible trend I've seen is a 3.5 rear gear. I've got a few emails and PMs out to get more info.

 

Your clutch fan is the most economical and efficient solution if it is working properly. Don't waste $$ on an electric.

Forget the Tornado, they are a gimmick that just lifts $$ from your wallet.

Weight reduction is good but keep the tailgate. Wind resistance will increase if the tailgate is removed far exceeding the gains from weight reduction.

A manual transmission conversion really requires a donor truck where you can swap parts. Your time and the price for the donor truck will determine the cost. But as I mentioned it will cost $$ and as others pointed out are hard to recover with gas savings.

The 460's do not have better heads, just a slightly larger version of what is on the 400 as they should have for the cubes. Cubes per mile and cam efficiency are what drives mileage. The dyno tune will be your cheapest option and may surprise you. I got 12MPG from a completely worn out stock 400 in a 78 F250.

 

I'll list some ideas, some are expensive, you will have to figure out what you will want to do over time,..


1) If you have a dual exhaust, put an H between the two pipes before the mufflers. It's a simple way to help the low end torgue and sometimes use less gas.

2) Ensure your vacuum advance on your distributor is working correctly.

3) Get some iridium plugs for a hotter spark.

4) Add some sort of spark increase, MSD box, Jacobs, etc. Something that increases the spark dwell.

5) Buy a set of close chamber Australian cleveland heads. They increase your compression and your corresponding milage about 1.5 mpg. Be prepared to spend some money on that though, and you would probably have to use a higher octane fuel rating, so it's personal choice.

6) Throttle-body fuel injection (big money).

7) Undersized belt pulleys. Not sure if they make any for the early ford trucks though.

8) Make sure your are running at least a 185 degree thermostat. There have been some studies on water friction within engines, and 185 was supposedly the minimum to run with.

9) If you are doing a considerable amount of highway miles, look around for a windage tray for your oil pan. They are mostly for upper RPM's but can help stop some of the oil splash on the crank at steady RPM's (which would create the effect of the water on bicycle wheels inside your crankcase). That one is a matter of choice since there seems to be arguements for and against it, so you decide.

Hope some of these can help ya.

 

I've heard about the thermostat a couple times. Mines a 180. Stock is 195 I think. Sounds like an inexpensive test.

 

I get a consistant 13.5 MPG with my 79 F150 (400/4spd/4wd/3.50), mostly rural highway driving. I am adding larger diameter/ narrower width tires to try to improve that a little more as I am turning around 2500 rpm at highway speed. Also going to straight up timing set. You could try adding a small airdam under the front bumper to reduce drag. I am trying to find one from an '87-'91 F series that I can modify to fit.