gas mileage.

[1970f100x]

What kind of gas mileage does a 360 bump have?

[FORD428CJ]

You should be able to pull 15mpg when everything is set-up right. It also depends on gearing and tire size too. JMHO

[willowbilly3]

12-13 is about all I ever got from one. 15 once or twice on one with headers and driving 55.

[ok68crewcab]

I have a heavy foot and 4.11 differential and feel proud when I get into doule digits. Its a crewcab longbed and does have some extra weight to it.

[Brokenarrow]

12-13 is about all I ever got from one. 15 once or twice on one with headers and driving 55.

You say you got 15+ from a 3/4ton 4wd FE truck with 4.10 gears. But you said there's no way my 1/2 ton 2wd with 2.75 gears got 18+ That's at least 700lbs weight difference, and the 2.75 rear is equivalent to adding an overdrive.

[averagef250]

Don't change the subject!

I believe it, I absolutely believe you can get 20+ MPG from an FE truck, but FACT is you are running the engine way too lean and will burn it up in time.

It's rediculous to think correct mixture can be had while running that lean. A very, very sharp machinist that is very well known and was building FE's when they were top of thier classes in racing (and still builds them) has told me time and time again that 12 MPG from a truck FE is it to get any life from the engine. I've seen the same firsthand. I got 16 MPG freeway once in my 70 F-250 4x4 from a very nicely built mild 390, 435, 4.10's/35's and 7000 pounds. I told my machinist about my tinkerings, he rode in it with me, told how fubar I had the carb, fixed it and I went back down to a consistant 12-13 MPG empty and 10-12 towing more weight than the law allows and 5 around town/short trips. I added an NV4500 5 speed at one point and overdrive made a negligable difference in mileage.

I would definitely call BS on anyone who claims they get a high average MPG and all they drive is short trips. I've owned lots of FE's and the darn things don't truely warm up and get decent mileage for 20 miles.

15 freeway in a light 2wd is possible with an FE, 18 is not. 15 MPG average is NOT possible. If you drive short trips shoot for 8 and be happy with 10.

[Brokenarrow]

Don't change the subject!

I believe it, I absolutely believe you can get 20+ MPG from an FE truck, but FACT is you are running the engine way too lean and will burn it up in time.

The subject was FE gas mileage. And I never said 20+. She would get 18 on a regular basis, that's on level highway, without a load, & not fighting the wind, and If you stayed out of the secondaries.(Carter Quadrajet) And I did see 20 a few times with a good tailwind.(This is Oklahoma) I checked the mileage quite often because I didn't believe it myself. Stop and go driving was about 10mpg if you bumped the secondaries every now and then. Yes it was running pretty lean on the primaries, and It was only turning about 1800rpm @ 55mph. With 4.10 gears it would be turning around 2700rpm. That's the same as driving mine in 2nd gear. So here's my point, Why is a claim of 16mpg with low gears realistic, while 18mpg with "overdrive" gears is not?

BTW, When I built that engine i just honed it, polished the crank, and went standard. She was built a little loose.It thrashed @ about 80,000 miles.

[binder56jd]

when the fe was mfg'ed--fuel economy was not on anyone's mind--it's a moot point--fe's use fuel like women use toilet paper--a lot and often

[Brokenarrow]

when the fe was mfg'ed--fuel economy was not on anyone's mind--it's a moot point--fe's use fuel like women use toilet paper--a lot and often

This is true. And I'd say you're machinist is right about the "longevity factor" when running an engine too lean. But back then that old truck was my only transportation, I didn't have a whole lot of gas-money, I was driving a ways to work, so I tweaked on it a LOT. (My dad always said I suffered from tinkeritis) FWIW, I don't imagine the overdrive gear would be feasible in a 7,000lb truck, but it works in a 4,000lb one.