I was just curious what kind of mileage everyone was getting with their 351w. below is what I'm running and the best I can get is 11 mpg.

87 f-250 4x4 4spd with 3.54 gears 33" tires
74 351w bored .020 over
small chamber heads (60.4cc) w/ 1.84 I/ 1.54E with the smog bumps removed and a little work on the exhaust side.
crane 260 cam .456 lift I/E installed 4 degrees advanced
9:1 comp. ratio
factory 4bbl intake
holley (motorcraft) 4bbl carb
duraspark ign. with base timing set at 14
headers with dual 2 1/4 exhaust
I run 93 pump gas

 

the best i got was 12.6 on a tank on the truck in my sig

 

15mpg consistent in my sig.

 

15 mpg here.

 

16 or 17 hwy with the E4OD, 10 or less with the C6. With 3.55 gears and 31 inch tires.

 

I KNEW I needed an overdrive. 11.5MPG w/C6 3.00 gears and 235/75-15s. Gotta get the 4.9 back on the road. Consistent 15-16, occasional 19 HWY. Been thinking about an AOD for the 351. Anybody running one? Will it hold up Okay? What about after mods? (mild cam, Performer intake, Fact. Lightning Headers & true duals--just bought the headers for $20).

 

<cr>
351W 4V - Complete rebuild about 15,000 ago - 3/4 ton 4x4 4-speed with 4.56 diff

10 m.p.g in town
10 m.p.g on highway
10 m.p.g pulling a travel trailer

 

What size tires? 1:1 final?

 

31"

If the 1:1 reference means the final drive in high (4th) gear, yes. I have no overdrive.

 

How fast do you cruise on the hwy? rpms? 10mpg seems pretty good for ever getting 4.56's on the hwy at all, on 31's and no OD!

 

It doesn't seem very good when I'm paying $1.75/gallon for gas .

I usually crusie along at 60-65 mph. Don't know my rpm's

 

16- 17 mpg

 

My calculator say 3215rpms @ 65mph!

 

My 2wd 78 Shord bed w/351W dual pipes, edelbrock dual plane intake and edelbrock 600 carb gets about 10 mpg @70-80 MPH. between 10-13 in town depending on the heaviness of my foot. Considering switching to fuel injection for better mileage and for the fun of doing it.

 

has anyone ever heard of getting a gain in MPG just by changing the PCV valve