I have a 76 f250 360, c6, np203, 4.10's, on 33x12.5x16.5 Mastercraft Courser MT's. I've done some tune ups on it and just got a new reman carb for it (Autoline 2100) I have been driving it back and forth to work this week just to see what I'm getting for mileage. I know its going to be bad but anything over 10 and I will be amazed.

I drive about 12 miles one way to work on flat highways with about a half a dozen stop signs along the way. I've been keeping it at 55 mph at 2600 rpm's. Taking off just like granny at the stop signs.

Here's some things I've noticed so far sense I have been driving my old beast. It ride sooo rough! Anything your taking with you might as well set it on the floor board because that's where its gonna bounce and rattle down to. My suspension is all stock and worn way out. I've road in other leaf sprung trucks of this vintage and they are a lot better then mine so complete new suspension is on my wish list. Also its hot as hell in the cab sense I tore the old rotten rubber floor out. I need to get my ac up and running again. But its a 76 model what can I expect. I'm still having more fun driving it then any other of my vehicles.

So far I have driven 80 miles and my fuel gauge is in between full and 3/4 of a tank. I drove about 40 miles before the needle even started to move from past full. When I filled up I filled up! clean to the top of the filler neck.LOL I am checking everything with my gps and on my gauges. My speedometer and odometer are off by just a hair.

Wish me luck guys. I will report back on my mileage... hopefully good news!! What are you guys getting for mileage??

 

Gas mileage is like a cheating girlfriend, I'd rather not endure the heartache of knowing.

 

73 shortbed 4WD, 390-4V, Edelbrock 2105, long tube headers, dual exhaust, NP435, NP203, 3.50 rear gears on 35s = 9 MPG at 55 mph indicated.

70 longbed 2WD, 360-2V, manifolds through a single 2.25-inch exhaust, NP435, 3.50 rear gears, 30-inch tall Bridgestone Desert Duelers = 12-14 MPG at 60 mph indicated.

Buy Exxon or Chevron stock.. you'll feel better.

 

I just keep telling myself I have a small gas tank. I think it about a 18 gallon in cab tank. Of coarse my mustang has a much smaller tank too but it also get 3x the gas mileage i'm thinking the highboy gets. Of well smiles per gallon is where its at right.

 

I got 115 miles on it so far and I haven't hit half a tank yet boys! I will say once the fuel needle gets to moving it does more pretty quick though. I've been getting a lot of friendly waves from all kinds of people on my way to work... mostly guys in older model ford trucks... wonder why? Aint it great!

 

once that needle swings below 1/2 I swear they start gulping the fuel.
The gf analogy is funny because it's true..
I'm curious; but I really don't want to know. I just figure I'm going to get 8 mpg and anything above that is a bonus! well I hope it's at least 8 and not lower...
PS: not enough miles under the wheel and a bummed up fuel gauge prevents me from knowing what I actually get at the moment.

 

Well, have you ever opened up a fuel level sender? I replaced bad one on an ol' 76 F150 back in the day and figure out why.

The sender has a winding upon which and arm connected to the float 'wipes' and transmits the measured resistance level. The one I took apart revealed the reason...the windings weren't distributed evenly - the upper half had large gaps so the resistance wasn't reading based on the actual level. It was "slow". As the windings got closer and closer together and the fuel level dropped, the resistance eventually became more accurate and it appeared that it was using more fuel when in actuality it wasn't. So now you know.

The rig? A 76 F150 long bed/302/C4 and it got 16 mpg.

 

Dang 16 is a pretty respectful number. The in cab fuel tank noise is pretty animated to say the least. Lots of movement and fuel sloshing. I'm used to it but first time riders get alittle unnerved.

 

'76 highboy w/390 & 4.10's = 14MPG when driven like wild man. 17 when driven like granny. GPS verified.

NV4500's rule.

 

I filled back up today. I drove 135 miles and was alittle past half a tank. I compared my odometer reading to my GPS and over 135 miles my odometer was about 4 miles behind.

Remember how I said I would be amazed if it got better then 10mpg? Well it amazed me... 10.05 mpg!!!! That is using the numbers from my GPS with I believe is the correct mileage. This was mostly highway mileage. My max speed was 57.8 going down a slight slope. My average moving speed was 40.4 mph. Tried my best to stay at 55 on the highways

Someone needs to make a 4th gear for a c6!

 

ford did, they just added a computer at the same time unfortunately.

 

An NV4500 with 4.10 rear gears results in a final drive ratio of 2.99..... That's way cool.

 

My 351m I had with a c6 and a 2.75 rear got terrible mileage when I had my 77.

Now my 75 I have now, back when I had it 2 years ago with a mild 302 with a 2 barrel, 3 on the tree with 3.90's would get 20 mpg no problem speedo and GPS verified.

Now that I've got it again and have a little bit more wilder 302 with a 4 barrel I get 15. Which for the cam I have I feel is respectable. Granted this was all city. Highway it dropped.

 

just imagine what you could do with an NV5600...

 

I can!.. but my solution will be a TKO-500 to find out if 20 MPG is possible with an FE (on my 70 Bump).