Well, I have a '77 F250 with a 460, automatic transmission, and 4.10s. When I first got the truck, it only got about six miles to the gallon. I've since had the exhaust dualed out to two inch pipes with twenty-four inch glass packs. I've overhauled the carburetor and adjusted fuel/air mixtures, choke, timing, and idle speed with the help of my dad. I drive it as economically as I can and I'm getting about nine now. When I can afford to do so, I plan to swap the rear-end gears for 3.54s (I don't have anything real heavy to pull) and I hope I can get twelve or thirteen out of it by then. Am I thinking right? Any other suggestions or ideas? Also, in the meantime, I'd like to know how fast I can drive it with these gears in it without blowing her up. What would be the maximum RPM you would want to run this stock 460 at for an extended period of time? Thanks guys!

 

Did your truck have the three-speed automatic though? My RPMs I think are quite a bit higher at freeway speed.
However, I had been having some truoble with my tach, but I think I got it set where it should be now... I just haven't gotten out to the freeway since. I'll see what it reads at seventy-five the next time I'm out there. Would I not want to push it beyond forty-five hundred RPMs with a big block or where should my limit be?

Thanks for the quick response.

 

Is it worth dumping all of the money into increased mileage on a truck with a huge V8 that is shaped like a brick, or would it be better to just get a more efficient vehicle? Now obviously you're not going to haul your boat or a load of wood with an escort but you're not hauling stuff everyday, you are driving to work every day though. Not to be a jerk, but it seems pretty hard to squeeze any gas out of these trucks, they're heavy and have 30+ year old technology, i think it's just a matter of dealing with it.

I have a 78 that gets OK mileage but i can't drive it everyday...no way... It's just the way it is.

 

Duke78, I hear ya... I don't drive the truck everyday (and usually only a few miles when I do drive it). I have a li'l '95 EscortLX that I pull a little over thirty miles to the gallon out of. However, I'm still interested in getting what I can out of my truck, so I can drive it to shows without breaking the bank.
UTfball68, now that I think my tach is doing what it should, I believe I am turning about four grand at freeway speed (I'm on stock tires).

 

well the 460 usually gets between 6-8 anyway. if you get a little bit bigger tires on it and slow down to 65 you can gain about 2 mpgs.

 

On your tach, move the switch from 6 to 8 cylinder....

 

That's exactly what I did and that's why I think it's working right now... at forty miles an hour, I'm turning 2100... 'bout right?

 

Tire size, and gear ratio? 2100 seems within reason at that speed. Sounds like at 80 you'd be passing NO gas stations....

 

Gears are 4.10s... tires/wheels are stock (Thirty-two inch, right?).
Back when the tach was reading to high, I never pushed it over seventy-two miles an hour because that showed forty-five hundred on the tach. Now that my tach is right, what should my limit be for an extended period of time without blowing up (max RPM)?

 

Thank you very much for the info.
Also, just for kicks, I'll ask... does a K&N air filter REALLY help noticably (fuel mileage and performance I mean)?

 

Thanks again!
I hope you guys don't mind me starting out here with a bunch of questions... I'm not much of a gear-head, so I need help sometimes.

 

Well on your c-6 how many miles on it. I once had a torqueconverter built for my truck just for the purpose of getting better mileage. I still run that same converter today. It was built by Tci. When I did this I had destroyed several other converters in the process. Sent them mine and we learned on what not to do. One thing to do is get tranny checked and see what pump pressures you have on c-6. Back when I built my converter with little slip/stall in converter. If its slipping your not moving meaning wasting fuel. They now make a towing converter that is similar to what I had built yrs ago. TCI - Performance Transmissions and Torque Converters good info on c-6 and some cool performance stuff also. As a guide on stall converters you need to be turning twice the rpm as stall to get the most benefits out of it. 2000 rpm stall needs to be turning 4000+ rpms to really work it. Camshaft is another factor on where your torque comes in. Stock is around 2500 to 3000 peak torque. Also on carb on 460 I think 750 with 1 to1 linkage would be nice with annular booster. Annular helps vaporize fuel better on low end. I personnaly run this and my 40" 77 ford makes 10 to 11mpg at 2900rpm down highway at 78 mph, I have 9" of lift also. I had a cam cut for my application it cost me 190 bucks for cam. People keep telling me to go smaller on carbs but a well tuned 750 on 460 cubic inch is nice. The 1 to 1 linkage will almost increase torque by third more. If your making more torque down low means less rpms in engine meaning less air fuel going through engine. I built some carbs back in the day because nobody was doing cool stuff. But these days these products are easily available compared to the old days. Been playing with quick fuel carb lately and priced decent and work. Just tuned a 498 in big block dodge with 830 downleg carb one to one linkage. about 34" tire 4.10 gears One ton crewcab makes 13 to 14 on highway. I think he's turning about 3200rpm.One problem with smaller carbs are they draw to hard on bores which draws to much fuel from carb with big cubic inch If your carb isn't adjustable on air bleeds this could mean bad fuel mileage. The smaller carbs are very responsive but go flat on top end. You have to jet and time your engine and all the other basic stuff but this is what I do and believe in and run. Those guys in enginemaste competition with trick carb on 470" 2500 rpm to 6500rpm are running around 1100cfm carbs. Apparently they know something most people don't. Also tire pressure is a huge factor when making mileage also. Need some more info on your situation to help out. the kinda mileage your talking is telling me something else is wrong with your truck.

 

don't know to much about 460s, was there a different automatic tranny in the 80s? i can't seem to remember there being one? i am thinking there is a 4 speed auto for the 460? i know ford made the 4 speed AOD for the 302/5.0 in the 80s but what about the 460s? did they get a new tranny too?, just a idea if they did, or i hear you can get a overdrive kit for the c-6 tranny? but its a lot of money from what i hear. and all you can do is make sure the engine is getting clean cool air and has a regular tune ups and you wax it regularly lol to keep the drag down on the air! lol and you can do many little things, like not carrying extra weight in the box, and keeping the tailgate up! mythbusters proved the tailgate down was worse on mileage do to air dynamics! and don't drive with a heavy foot, and let off when you come up to a red light, and don't do jack rabbit starts lol and thats about it, you can play around with gears too, and tires but its a tricky game, and a propane conversion might help too? not sure? all of these things cost more money sometimes then the gas saved. Good luck with your gas mileage experiments, there's more than a few of us looking for more gas mileage.

 

The 460 got a new transmission in the early 90's, the E4OD. The other option is an external overdrive unit. Both are spendy, but I think I would rather go the external overdrive route. Unless you got the OD unit cheap, it would take a long time for the savings in fuel (especially now that its on sale for 50% off) for the savings to pay for your modifications.

 

true that, and thanks for clearing up the 460 auto tranny question, and i know gas is cheaper, well up here in London, Ontario its about 75 cents a liter, and its height of price it was at 1.40 a liter! and even at 75-80 cents is still a lot compared to 2.80 a gallon down in the good ole U.S.A.! and you never know! the gas can always go up again! which i fear will happen, we really need to drill our own oil offshore and in Alaska and parts of Canada too!, but that's another issiue all together