Hello....I'm a retired ol' fella and have just had an old ranch truck fixed up for myself. It's a '76 F150 2WD flatbed. iT 'S IN NICE SHAPE WITH A VERY CLEAN INTERIOR AND i REALLY LIKED IT. A good mechanic in town just got done installing a freshly re-manufactured 360 V-8 in her. He also had to rebuild the Holly 4 barel carb. It's running good, but much to my dismay, testing the mileage over a 80 mile course today, I ony got 10.1 MPG running 65-70.....then 10.6 MPG between 55-60. This is alarming. My mechanic said that the holly wasn't origional equipment. Could any of you boys suggest what I can do to improve this??? Would a new 2 barrel carb help?? If so, which one would you suggest. I got a pretty good amount of money sunk in this pickup....but dang, it'll eat up half my pension check running around with gas prices what they are.

I know most of you fellas on here do your own wrenching (which I envy), but any suggestions you'd be willing to give this ol' knuckle buster would sure be appreciated. ThaNKS.

 

Your only real option is a gearing change depending on what you have now. At the absolute best with a 360 I wouldn't expect more than 12-13 mpg.

 

My first pick up, when I was a teenager, was a '73 F-100 with the 360. Short of re-gearing it with a high-speed rear, that's about the mileage I would expect from a 360. They were NOT known for fuel efficiency. Keeping the rpms down will help some, but not much. They're just a thirsty engine.

 

Two barrel carb or 4 barrel carb is going to give you about the same gas milage .If your getting 10 thats about normal .Duel exhaust may help if your running single now . What gear ratio and tire size are you running?

 

Ouch!! Tires are LT235-75R 15's. My guess is the rear end is 411?? She pulls like a tractor. If changing to a highway ratio would only goive me a mile or two more per gallon....guess that would be just throwing more good money after bad. I've got over $4000 into this project right now....don't think she's worth it. Oh well, no fool like an old fool I guess!!!

 

Installing taller tires would lower gear ratio helping gas milage you would have to change your speedo gear when going to a taller tire

 

Alarming? There's nothing alarming about it! These trucks have the aerodynamics of a brick, a gallon of regular gas was about a buck back then and...NO ONE gave a hoot about MPG!

The engine is tight, why the MPG is low. When it loosens up, expect 8-12 MPG city, you might see 15-17 MPG hwy if you drive 55.

All 360's were 2V's, someone either swapped in a 4V manifold from a 1965/71 390 Ford/Merc Passenger Car, all of which came with Ford (Auto-Lite) 4V's.

Or, a 1974/76 F100/350 390 4V manifold was swapped. Some of these came with Holley 4V's, some came with Motorcraft 4V's.

Look on the manifold for an ID number, post what it is.

Rear axle ratio is probably 3.00/3.25/3.50 or maybe 3.70-1 as these were the common 9" ratios for 1973/79 F100/150's.

 

4k...... I have like 27k into mine and still needs paint, suspension, bed liner and a new engine and tranny rebuild Hope that makes you feel better haha. Mine was one mistake after another with a mechanic who ended up not knowing what he was doing snd up till now with a few other costly issues, I know the frigin truck inside and out. I see now what I shoulds done different and woulda saved me 10k maybe but hey its a learning experience. Dont ever want to sell it so oh well.

But yes change your gearing or if you have a 3 speed auto get a gear vendors overdrive as well if you keep the truck forever.

 

Thanks for the reply....I looked on my manifold this AM...it's got two sets of numbers I could find: 66AE, above 9426-F. Then looking at the metal vin plackard on the door I find it lists the axle as 14J, does that tell what the ratio is??

I appeciate each post with advice I got, but what is your opinion concerning my delema? If I changed to 16" tires, added a 2nd exhaust system, had an over drive installed and found a highway rear end....what would be my potential best case hope for MPG? I'd sure rather hear the truth from you guys on this forum, then listen to my mechanic, who would have a vested interest in me spending more of my savings.

 

Look at it this way: if you bought a new or at least late model pick up you would spend what...$15k minimum? How much gas would that put into what you have now and how long would that run you? Plus, what would insurance cost on a new one? Also, you don't have high-tech computers to go out, sensors, etc. These old rigs are much cheaper to repair when it's needed than a new one.

That's how I rationalize it, anyway....

 

66AE ~ First 6 is letter C ~ C6AE-9426-F = 1966 Ford Galaxie/LTD 390 manifold.

14J: 14 = Ford 9" Rear Axle / 3.00-1 / No Limited Slip / 3,750 lbs. Rear Axle Capacity // J = Power Steering.

 

Cowboy, that's pretty much par for the course with a FE in one of these trucks, 10-12 is about average.

You're doing better than most, not as good as some others, you may get closer to 12-13 with the mods others have listed above, but it doesn't get much better than that.

Are you in the eastern flat lands or out west in the mountains?

 

We're all over this board! Haa. Good luck, dude. I just acquired an old 73 F250, it will be interesting to see where it's at gas mileage-wise, but that's not the reason I bought her. I've always wanted one of these old rigs, and I knew going into all of it that it was never going to be an economical or smart project on any level other than my own happiness and piece of mind. Which is kind of selfish, but at this point in my life, if I don't treat myself from time to time I'm going to wind up a miserable son of b.tch! And I ain't trying to drive this thing across America when I get it running, either. Welcome to the deal....

 

Hello fella Montanins....Nice knowing I'm not the only one up here. My place is outside Miles City bout 20 miles or so. I found this old truck and thought it would be cool, fixin' it up so I could save miles on the dually. It really is a neat rig. Inside is so much cleaner then you'd expect. Dash, headliner, instruments all in extra fine shape. Old man kept it in his barn when he wasn't using it I guess. Everything works...gages,, lights, radio, except for the horn. It did need a seat cover, and will need a new floor mat. Anyhow, I had this new re-manufactured 360 installed and as I said was somewhat dumbfounded with the mileage test I did. Filled up in Miles City, and ran as close to 70 as I could keep it over th Glendive 80 miles away. Got 10.1. Comeing back at 60 got 10.6. From what I've read here, sounds like I'd be dumb trying to improve by putting a whole lot more money in it chasing only a few MPG.

Bottom line is she runs good, sounds cool, and makes me feel like I'm a 35 year old red neck again. Thanks for the input by the way.

 

Man you guys are in MONTANA,you dont have to go anywhere.