Gas Milage in EB

[blubuckaroo]

I too asked about fuel mileage on another eb site and immediately got flamed. A lot of responses about "cool factor" and "who cares about gas mileage ".
The reason I asked about mileage was my bronco at that time was a 73 c4 with shift kit, 351 Windsor, 31x10.50 bfg. 4:11 gears.
Best I could get was 10 mpg.
My prior broncos would get around 15 mpg.
My 70 pure stock 302 with small tires,4:11 gears leaded regular gas and lived at 5000 ft elevation would get 15 mpg.
My 71 stock 302 small tires 3:50 gears, also. Ieaded regular gas low elevation, also around 15 mpg.
I think that the smaller tires make a big difference in mileage. Those large tires are like 4 big flywheels to turn along with the rolling resistance.

Even with corrected gearing, bigger tires have several things that negatively affect mileage.
The greater centrifugal weight take more power to get rolling.
The rolling resistance of bigger tires takes more power'
Wider tires are less aerodynamic than narrow tires.

Also, many don't realize that a well tuned engine will be an efficient engine. You can't just take a carb or distributor out of the box and expect it to run right.
Last year we attended the Northwest Bronco Roundup, and you could tell the well tuned Broncos by the smell. I'm sure the stinky ones are missing out on efficiency and performance as well.

 

[661buster1963]

With my bone stock 2 barrel 289, and shifting 3 on the tree I was getting 15-16, took a year to future out the horrible vibration was from lack of a double car an drive shaft. Fixed than started getting 17+
Then I decided to needed to make it more badass and went to floor shift 3 speed, put a Holley 465 4 barrel on it and some 31”, then 33” tires and 4.11 geared the whole time and got about 9-10. That was computing true miles as I adjusted the real mileage after a 10 mile run on a road with a speedometer check (like they still have those anymore). Now going to a 351w flat tappet, 4.56 gears, np435, 35” tires and I expect to get somewhere around 8, maybe 9 and to smile about 450 ft-lbs and how it ‘seat of pants’ feels. Fun to occasionally though I don’t personally endorse it, stomp the crud out of a Chevy or a J**p poser wannabe who thinks they have a badass ride. Scouts semi still rock though.