Old topic [gas mileage] revisited...

[1986F150Six]

While searching for something else, this popped up and I wondered if any of the newer members might be interested in the topic of improved gas mileage in a Bullnose truck?

https://www.garysgaragemahal.com/#nabble-td39075

[Ford F834]

Very good thread, David!

MPG has always been a a favorite topic in the IDI world, but it is far less talked about now than it was 10-15 years ago.

I’m guessing that is because fewer trucks are being used for work and daily driving… and more are being rebuilt as classics or recreational use.

I have not yet resolved the speedometer issue in my 81, so I have no convenient way to track cululative mileage… but on my recent heavy haul from Camp Verde to Golden Valley I was not disappointed with the fuel consumption. In spite of all the neglect I’ve dished out, the 300 is still doing very well 🙂

[FordFETruck]

I remember that from years back. I've never gotten anything but 8-10 MPG out of my truck other than one time I got 12.5 and 11.5 towing a car on a car transport trailer for about 100 miles. Nothing I've ever done to it has made it any better and it doesn't matter much how its driven either. Maybe the new engine about to go in will be a little better but my experience has been a carbureted Ford V8 with a 3 speed auto good luck getting any better than 10 no matter what unless it's strictly highway for the complete tank of fuel it might get a little better but not much.

On another note one of my coworkers has a 96 or so F150 short bed RWD, 300 with a ZF5 and he barely clears 12 MPG or so with it driving it long distances on the highway. That truck is very high mileage and tired though. I think that one has somewhere around 350,000 miles.

[mat in tn]

I will start by saying that I drive like a grandpa most of the time. my wife makes comments. haha. but I see varied results as I have the opportunity to drive a few different of these trucks. my best hands down is "dolly" a 93 flare side (known for their streamline aerodynamics) with 5.0 efi , aod, 3.73 gear, twin tank truck that on long trips on the highway I have reached 19 mpg at roughly 80 mph avg. generally15-16 around town. im driving a little mor conservatively trying to break the 20 mpg mark.

[1986F150Six]

Ford F834 wrote

Very good thread, David!

I have not yet resolved the speedometer issue in my 81, so I have no convenient way to track cululative mileage… but on my recent heavy haul from Camp Verde to Golden Valley I was not disappointed with the fuel consumption. In spite of all the neglect I’ve dished out, the 300 is still doing very well 🙂

Jonathan, many years ago, the rear gears in the 1984 F150, which belongs to my son, were changed from 2.47 to 3.55. A variant of the following was used and is still working!

https://www.ihpartsamerica.com/store/SPEEDO-GEARBOX.html?gad_source=1&gclid=CjwKCAjwupGyBhBBEiwA0UcqaOIBAYZqImP-K7lYhQkFj6QcCQidhTmPb8k4VRFjetvDI8VMmjZMkBoC6LEQAvD_BwE

[Rockhauler]

With my 300 6cyl 4x4 3.55 diff RTS 4 spd overdrive I found the sweet spot was around 80km/h (50m/h) on the highway. I've since gone to 31" 10.5 r15 tires that often forces one to shift out of overdrive going up big hills. Haven't clocked my mpg with the bigger tires but know its not as good as with the 235 75 r15 tires.

I think the best way to increase your fuel economy is adding a overdrive. That said this only helps at highway speeds and not towing a loaded trailer.

I'd love to put a 5 spd overdrive behind my 6.9 diesel but haven't been able to find one at a reasonable price yet.

Paul

[mat in tn]

so, I refueled today. 600 miles from the two tanks. mixed driving as I take about ten miles highway out of the 27 going back and forth from the shop when I go. about 75 miles on highway going to trans parts wholesaler but mostly back roads and town for the rest. averaged 18.70 mpg. this tells me 19 is well in range and 20 may be if I really try. this last fill was 107 American so I feel motivated to try!

[Gary Lewis]

I, too, usually drive like the grandpa I am - in old trucks.  (Don't expect grandpa when I'm driving our other vehicles with turbos as you need to keep them lubricated.  )

Big Blue will turn in 12 - 13 MPG if I keep the speed to 65 MPH and manually feed it.  But that gets painful so I put it on speed control and it'll get 11 - 12 at reasonable speeds.  Not bad for a 460 carrying 6500+ lbs on its back.  Oh, and there's very few mountains it won't climb in 5th gear.

Dad's truck, though, is more frugal.  When I got it with the stock 351M/C6/3.50 combo it got 10 MPG.  And wouldn't climb nor accelerate very well at all.  When I put Rusty's warmed-over 351M and the ZF5 in things got a whole lot better.  We ran 65 - 70 MPH on a 3000 mile round trip to Delaware from Oklahoma delivering a bed FULL of furniture and got right at 14 MPG - using speed control the whole way.

So I'm here to tell you that the C6 is a waster of fuel, and an overdrive can change everything.

[mat in tn]

lubricated! tell it to the judge. haha

[Ford F834]

I remember that little gear box David! Quite cool. I still want to try my idea of pairing the metric speedometer head with the white driven gear to see if miles will read as kilometers… but I have not been able to justify the downtime to switch out the drive gear in the BW1345. But it will happen in due time.

Right now I have no speed or mileage indicator at all. The truck is serving its term as a burro I guess… I don’t have much need to know exactly how SLOW I am going… 😅

[mat in tn]

now here is a man not afraid to "load" his 1/2 ton truck! stay off the scales !

[BigBrother-84]

Ford F834 wrote

I don’t have much need to know exactly how SLOW I am going… 😅

Lol!
Having front wheels touching ground enough for steering it?


Big Bro uses to slowly tow a manure trailer, once a month.
He probably drinks 12 gpm while doing his duty.


Sometimes we hit the road, mostly highways, with some streets and small roads ride too.
Average 12,3 mpg.
Without heavy load.

[Gary Lewis]

Good point, Jeff.  Forgot to report on the trip where Steve/FoxFord33 and I took Big Blue and the car hauler trailer to Stillwater and back to get a Mercury Mountaineer.

The Mountaineer is said to weigh ~4500 lbs and the trailer is about 3000 lbs, so we were towing 7500 lbs. On the way over we ran 65 & 70 in 5th gear and the 460 didn't care.  But on the way back we mostly ran 65 in 4th gear 'cause it took a lot of throttle to pull the hills in 5th, and there are some pretty steep hills on that trip.  But it went up the hills with no problem at all in 4th.

Round trip it was pushing 200 miles, with a fair bit of time idling to get the trailer into position or charging the battery while using the winch.  And overall we got 10 MPG.

As for the front tires, I don't think they got much wear on the way back.  We got that Merc too far forward on the trailer and didn't want to try to move it back given the D-shaped tires and the fact that it was stuck in Park.  I'd put quite a bit of air in the air bags so the truck didn't squat at all, but the steering sure was light.  

[Ford F834]

Yeah, my steering is pretty loose even unloaded… and then load on that much cement and the steering gets downright approximate 😵‍💫. Obviously I was not going fast enough for that to be a problem.

I did find a set of “helper” leaf springs in my junk stash, but my recollection is that those make for a very, very rough ride! Even the cement sack load in the picture didn’t have the stops to the axle, and I wouldn’t go any heavier than that! My F150 has a GVWR on the door tag of 6,100 lbs which is similar to the “light” F250’s with semi float axles but I was definitely over that time 🙃

Hauling heavy my mpg goes down to 10-12 depending on the grade and the speed, empty I’m 15-17. And the heavier the load the more I appreciate the close ratio T19

[Rockhauler]

The rockhauler name comes from my wife wanting some rocks to make a rock garden and me being a heavy equipment mechanic. She had no idea what was coming till I showed up with a rock in the back of my F150. It took 2 one ton chain blocks working together to lift the rock high enough to load into the back of my truck. This one particular rock and a couple others had the rubber bumpers on the rear frame crushed into the axle and the front wheels kind of skipped along when they felt like it. By the time I was done hauling rocks the box cross members were crushed and the box floor was touching the gas tank. Was worried at the time I would sheer off a axle flange. Wasn't really thinking about fuel mileage on this quest but did get the loaded truck up to highway speeds, to be young and foolish again.

 

Paul

[C.Jett]

Awesome job Paul, maybe she’ll let you off your knees now. Pun intended, no offense meant. After a good laugh, I know she loved it. CJ

[C.Jett]

I got 9 mpg when I first got my 1985 300-6, after new carb, fuel lines, fuel tanks, fuel pump, distributor, wires, plugs and fuel regulator. I now get 9.mpg! CJ

[Gary Lewis]

C.Jett wrote

I got 9 mpg when I first got my 1985 300-6, after new carb, fuel lines, fuel tanks, fuel pump, distributor, wires, plugs and fuel regulator. I now get 9.mpg! CJ

Just think, "I could have had a V-8" and gotten better mileage.  

[C.Jett]

I think you’re right Gary but I have not found one this solid, very minor rust and I can drop an 8 in it or sell it. Forgot to mention, I also installed an air dam on the front bumper. I believe the guys getting “high mileage” with a six has been hanging out with the Dodge boys. CJ

[Rockhauler]

No offense taken CJett, my neighbors likely think my head is full of rocks. I hate cutting grass on a steep slope so replaced the grass with rocks. Wife then planted flowers around the rocks turned out looking pretty good.
 
Paul