what kind of mileage do you guys get highway and city?

 

I get 11.7 mpg city or highway 72 f-250 390/396 500t@ 3500rpm, 370 hp@3800rpm c-6 modified dana60 4.10 limited slip truck weights @ 5960 with my fat butt and two bags of fuel 8k on rebuild at this time. Tim.

 

390428cjt, how have you built the 390? 500tq and 11+ mpg sounds pretty nice.

dbossman

 

11.7 mpg with 4.10 rears is even more impressive.

John

 

I always got around 8 with my 390 4bbl, C-6, 4.10 4x4 in my 75 250...

 

Where did you get your HP and weight figures? That seems heavy, unless you have a 4x4 or dually?

My 69 f250 2wd weighs between 4500-5000 depending on gas tanks and what junk I'm hauling.

My stroked 428, made 360 HP at the rear wheels. Through a C6 and Dana 60 with 4.10s.

I don't get anywhere near 11mpg. I have not really measured it, but I suspect I'm closer to 7mpg.

 

Last time I checked I got 8 mpg city and highway. I hardly do any highway driving and when I do it is with 1500-2000 pounds of wood so I can not really measure the highway driving accurately. Having the front axle locked in does make about a 2 mpg difference empty.

1971 (with a 1965 390) F-100 4x4 np435. I added about 600 pounds of steel to my truck in the way of bumpers, flat bed, and reinforced the rear frame every 18 inches. I imagine the truck is way over 4000 pounds.

 

gtex Did i forget to mention that it has a commerical cap for all my tools as Im a remolder/carpenter which add about 1k to truck weight plus a 3/8 plate steel custom bumper on the back/with reese hitch built in and its welded to the frame ( i would feel sorry for the person that would hit that) The power ratings were done on the engine dyno after three pulls and added 10% after breakin time which is where i have the estimate ##,s with the 4.10's Im about done @100mph 4900rpm the dyno # are correct and was built by a man who races in the nationals fords of course he's been racing and buliding fe's for 38 yrs was recommended by george guessford , hes building a 428 that he claimes will put out 500hp natural I'll have it by spring and i belive him after all expercing is beliving and the mialage is if i keep it around 3000 rpm or less 55 to 60 mph plus i run a demon 625 with the purple secondary spring it keeps the back barrels closed until i put my foot into it, so im using only 2bbls just cruising before i switch the spring i was getting 8mpg. That the facts and im sticking to it.

 

The details on build will take some time I have to gather all the paper work and specs and condense it as its alot of typing will post soon on it.

 

390428, thanks for the offer on your build specs as i'm also interested. Carl
.....o&o>.....

 

yep that sounds great.
I'm getting 9mpg, driving like grandpa, 10k on the rebuilt 390, 3k on the rebuilt tranny.
Mine is nothing special, desktop dyno puts it at 270hp and 390tq and mines never been loaded down.
Guy that built mine sair it should knock down 14-15mpg... schessh... I wish... that'd be 50% better!

 

I have a 68 F-350 with 360 and it gets 7-9 mpg, I also have a 66 F-100 4x4 that has a 67 Fairlane GT 390 Hi-Pro with a Elderbrock 4v and headers with duel pipes, all the rest of the running gear is stock for the 66, 4 speed and in/out tranfercase. This truck gets 11-12 mpg in town, I live in a very small town, and 15+ on the open road. I have had this truck sence 1979 and was put togather this way in 1980.

 

in theroy the 390 should pull 10-15 mpg but road cond't weather, specific setups, weight, drivers, tires,carbs setups etc yield various mpg numbers if i put my foot into it opening the back venturies I'll yield around 7mpg.Driving at 60 mph @3000rpm I'll get over 11mpg but also its winter time here so there warmup time involved here and that cuts into my mileage as you may know the fe's are cold blooded until fully warmed up.

 

60 with 3000 rpms is tooo high for good mpg, I think mine is turning about 2150 at 60.

To keep these big guys sipping gas, ya gotta keep the rpms down, and not run big ol cfm carbs that tend to waste it. IMHO

John

 

My stock 352 in a stock F-100 gets 11.6 mpg in the city. One time a couple of years ago I got almost 15 on the highway (still a little flushed from that experience).
jor