Guys

Need to know what is a decent fuel consumption for a stock 400 enginee.

I am getting about 1km/l is this ok? Or is it too low?

Regards
ray

 

I'm getting anywhere between 7-10 mpg outta my 79 250 400 auto 4wd hubs locked with 3.55's 33 12.5 16.5's But then again it all depends on how much noise I'm trying to make or how over loaded my trailer might be.....

 

Hi there;
I can get as much as 17.4 mpg (about 13.5 L/100km) if I try real hard. I don't have exactly the same engine as you but the numbers should be kinda close: 2wd, auto, F250, stock 351M, 2V, with a modest load of camping and travel related gear in the box. This was an average over about 500 miles (800 km). I don't know what the rear-end ratio is but I'm spinning around 2300 RPM at 60 mph with 235s. I guess I could figure it out but......I haven't done this yet!

Wayne.

 

wayne_nicolson just wondering if you misplaced a decimal point or something when you calculated 17.4 mpg? The most I ever got on my stock 351M was about 8mpg (thats with c6, 33x12.50's, and 3.5:1 gears and a freshly rebuilt motor stock except .040 overbore) and with some minor add-ons like edelbrock intake and 750 4-barrel it went up to about 9.5mpg. Driving it hard drops it down about 1-1.5mpg compared to my usual casual driving. My '99 4.2l v-6 only gets about 15 avg mpg, the most I ever got was 17.2; would be a site to see when a '70s 400 with 3 spd gets better milleage than '99 4.2L with 5 spd. just my $0.02

 

i got 13-14 mpg with my 400m when i got it and when i took it apart it had a burned exhaust valve and the bearings were toast it was in a 77 ranchero which is light by no means are you sure he isnt correect it the 17.5 ? i am hoping with my build up i will increase my mileage with a 4bbl 650 carb i think 750 is too big and mallory ignition.

 

wow he said if he trys real had he can get 17.4. depending on gearing and other factors, yes he can. there is a guy who had a efi 351c getting 28mpg. i would say that on the average 8-14mpg is average.

 

Ditto GT40!

 

Hi Guys;
Remember - I have to try real hard! This is by no means what I get driving all around town all day....and this was the average over a single 500 mile journey - very little stop and go action. I don't get this kind of mileage all the time either. I do, however, have detailed fuel consumption, mileage and other data for my truck since 1996. Nerd stuff I know, but this is the only way I can tell how different factors really affect my truck (and my wallet).

No, the decimal is in the correct place! Mostly, I drive this truck on the highway with no load. To further complicate matters, I drive it with the personal challenge of trying to get the best mileage that I can. As you can imagine, I'm a lot of fun to ride with <grin!>. I don't go for the "miracle fuel saver" gimmicks and I keep my truck well maintained but in mostly stock form. Any modifications that I do will not be for going faster but for getting better mileage. Over several years, my average fuel economy has been 13.8 mpg. Of course, it's been a lot worse than that at times. Also, I'm the only one who ever drives the truck so the way the truck is driven is pretty constant.

Here's how I get my numbers:
- distance traveled / volume of fuel used = mpg for a tank
- sum of mpg / number of tanks = average mileage
Since I keep general temperature data (only when it's very cold or very hot), the date and location of each fill and maintenance and repair dates and details, I can break it down according to what ever categories I choose; per trip, around town, city and highway combined, summer average, winter average, with smaller tires, short trips, extended trips, driving only in months with 31 days, etc., etc. I can also query my database to see if there's an increase or decrease in mileage when I installed a new air filter, packed the wheel bearings, etc.

I'm not trying to fool anyone or make wild, un-true claims in order to sell something. I just like driving my truck but it costs money and like everyone else, I want try to keep my costs down as much as possible. I would like to get much better mileage so the next modification will likely be EFI or an overdrive.

 

Ok Wayne, you convinced me. Still hard for me to believe though. Maybe it just makes me sick to think that mine is averaging about 8mpg. I still think there is something in the air up there

Were my wifes family is everyone has 70's ford trucks and the 351m/400 is all to common. Most of em I have talked with dont get much over 10mpg but also have old motors and several are geared for towing (mostly all are for farm duty). But I got my truck just 2yrs after the motor was rebuilt (all stock) and it only averaged 8mpg even on long trips. The only mod at the time was dual 2.25" exhaust and glasspacks allong with 33" tires and 3.50:1 gears. that should work out to stock drive ratio roughly.

But here is what I want to do, and I would like comments to verify that each of these items I think should improve gas economy:

- better cam with 'straight up' timing set (like edelbrock performer)

- increased compression (9 - 9.5)

- minor porting /polishing

- holley comander 950 tbi unit (feul injection)

- 5spd tranny swap (maybe a ZF if I can figure out how to do it)

- relatively free flowing exhaust (headers, dual 2.5", hooker aero chamber mufflers)

 

there is a guy on the network54 cleveland board running 2.74 gears in his 351 car.