Poor Gas milage

[ELI]

1970 Bronco, stock 302 2bbl, I am getting 9.4 mpg...uhg! Smells like she is burning rich...$5 gal. gas...not good! Any help or ideas, or know how to adj. fuel mixture would be greatly appreciated, or any other ideas.

[maui]

Convert to EFI. My mileage went up a lot. I don't have numbers but I definitely spend less time at the gas station.

[Scodge]

Buy a 1995 Honda civic for daily driving. You hear guys talk about 20 mpg in EB's, but I think those are fish stories. I've got a pretty mild rig, 33's, 4.11 gears and a 5.0 efi motor. I'm getting about 12 mpg with a tailwind. A truck with a carb is lucky to do better then 10 mpg. Tune your rig up, check your tire pressure, and install a vacuum gauge. The more vacuum your engine is pulling during driving, the better your fuel efficiency. Back in the '80's, BMW put fuel efficiency gauges in their cars. They were really just vacuum gauges.

[ahansen_1985]

Eli I might be able to help, where you from?
Also it is possible to see a bronco into the high teens.... It's hard to do, but it's possible:) I average 17 with mine...
But my setup doesn't work for everyone....

[ELI]

I live in SW Virginia, 1,100 ft. above sea level.

[ahansen_1985]

Well with that kinda distance best advice I can give you is that for milage you have to find a happy medium for
Your motor...
If you over gear it will bog to much
If you under gear it will be wound tight...

My setup prob won't work with your due to your 302, but you might be able to play with it...

351w, edelbrock carb, wieand aluminum intake, electric fan, headers, dual exhaust, electronic aftermarket ignition,
I'm running a m5od 5 speed, which gives me a overdrive, np205 tcase, and 3.50 gears with 35/12.5/15 mud terrains..

When I ran my 3 speed I averaged 15-17 depending on my driving,
With my 5 speed I'm averaging 17 more consistently....

I have just enough power in 5th to
Pull a small trailer without bogging, but if I want to pass someone drop er down to
4th, or even 3rd depending on speeds...

My bronco weighs 4200 lbs, with hard top and full size axles, but the whole front clip is not factory either

It's all finding what works best for you...

[rbarchi]

is your exhaust pipes black inside? I would tune it up to start if you are smelling it is running rich.

[DirtDonk]

Depends also where you're getting that mileage. When mine was a daily-driver (as opposed to a driveway queen) it consistently got between 9 and 11 with a mixed city street/expressway trip. Didn't seem to matter if I stayed cruising or stopped at lights for awhile. Same mileage.

Depending on accessories, on the freeway I consistently got between 14 and 17 mpg. The only time I could get above the magic 15.5 mpg barrier, was when I had a little Holley 450 cfm "Economaster" smog carb on it. Otherwise it got 15 and that was it.

And this was in a very modestly modified EB with a constantly tuned up engine. I'm a tinkerer by nature, so I rarely got more than a few thousand miles on it before I was twiddling with the carb, the distributor, air pressures and anything else that could be adjusted.
The mileage never varied whether it was stock original, or had electronic ignition added, swapped brands/styles of spark plugs, ignition control boxes, or any one of various 4bbl carbs mounted with various jetting experimented with.

So if your 9.5 is with mixed driving, or over hill-and-dale, that's not all that out of the ordinary.
Hope you can meke it better though.
Good luck.

Paul
It "ran" better each time I made a change, but never got better mileage.

[Stan]

Ya - what they said . Also What gears and what size tires ? Do you have a manual choke on the carb?
I find it difficult to check the gas mileage on these things - especially in daily stop and go and here and there driving. I've been able to do it a couple of times on " longer road type trips " where i knew the miles traveled and the amount of fuel used - two key components in the MPG equation. - Don't trust your odometer or the gas jockey filling your tank.
Stan

[ahansen_1985]

Stan did bring up a great point, milage is only accurate if the fuel is refilled to the same spot... I take mine till I can see the gas sitting in the fuel neck.... And I keep track of my milage via gps when I have checked it....

[Stock 68]

[SHAWN]

My odometer is right on...and mine is just a little modified.
When I still had both tanks, I use to put ten gallons in the rear and run it empty. That way there was no room for error.

Shawn.

[Stan]

Don't you mean "don't trust your odometer if you've modified your Bronco all to hell"?[/quote]
I wouldn't be assuming that your stock odometer is correct when figuring your mileage - i'd certainly test /check it out first . I wouldn't be surprised to find some of them off - say 10% -- that 20 gals of gas it took to drive 300 miles = 15 mpg . But if it was only 270 miles ; that's 13.5 mpg . You could ne lucky and have it off the other way; then that's 20 gals. for 330 miles and that's 16.5 mpg.
Stan
I use Shawns' method when i check mine

[Scodge]

Are there still gas jockey's anywhere?

[SHAWN]

[DirtDonk]

Mine was spot on as well (after I fixed it) and I always ran my tanks to empty then filled up with a known number of gallons.
So my calculations were as accurate as I could make them.

Paul