i just recently bought a 77 F-250 dent side with a 351M engine and a 4 speed transmission. does anyone have any thought on how to make it more fuel efficient?
If i have one i want to put a 5-speed transmission in it but i want to go further. as i said just looking for some thoughts.

 

Buy a Honda, theres not much you can do with 351, you may be able to shave a few MPG but thats about it.

good luck

 

Just put a Holley ProJection on my truck, Pretty strange going under the dash to tune the carb! Its not on the road yet but hopefully it will get better mileage.

 

There was a post on here a few weeks talking about the ROI(return on investment) of several improvements. I would take that route and figure out how much you drive in a year then see how long it would take you to recoup your investment. Headers or new exhaust pipes are 2 improvements. Changing the gear ratio in your rear end can also give you better mileage depending on the amount of city or highway driving you do. Somewhere around 3.5:1 is a good mix of city & highway.

 

upgrade ignition to some type of multi stike system. gearing as mentioned. Upgrade fuel system to a quality carb or fuel inject$ keep your tires skinny and good air pressure proper. On the speed tranny their is the zf-42 or zf-47 tranny 5 speed. The only problem is your gonna have some issues with getting the tranny fitted up proper. Your tranny shaft to back of engine is short. gonna have to modify your pilot bearing and several other issues. not impossible but your gonna have to use your head on this application. I'm currently working out the details myself to a 400 ford. 351m has a big block bolt pattern so you have to use a 460 zf tranny. the shaft to clutch plate has a bigger diameter splines which limits your clutch availibility. centerforce is about the best dual friction. their are others out their but have to do your homework. catch you later and good luck.

 

This topic has been beat to death (do a search), other than measures you would take to improve mileage on any other vehicle there's not much you can do, why buy a 70's era Ford pickup truck if you're concerned about fuel efficiency???, these trucks were manufactured when gas was 50 cents a gallon, mileage wasn't a concern back then (and shouldn't be now) it is what it is, you're driving around in a nearly three ton truck with the aerodynamics of a refrigerator so what do you expect??? buy a Prius

 

I disagree...refrigerators are WAY more aerodynamic than one of these trucks.

I have two slicks and a dentside at home. They're awful on gas. When I need fuel efficiency, I drive my Focus.

 

id say to advance the timing but the cleveland 2v heads are prone to detonation

 

look at a gearvenders overdrive work good with a 26% reduction in rpm but pricy

 

This is all good stuff. but know i will never give up the Dent-side!
... or drive a prius

When i bought this i wasnt really worried about fuel Efficiency (i knew what i was getting into lol) i just want to make sure i get the most out of this awesome Vehicle.

Thx for your Help

 

You're a good sport. 302's and 300's tend to do the best as far as mpg's are concerned. My straight 6 in my 79 4x4 could do a respectible 14 mpg or so (the way I drove it, it was more like 10-11). If you're gonna try some modifications for mileage, at least you're starting with a small block. I've had two FE big blocks, a 460 and a 292 Y-block (1964). Those old engines seem to lose a gallon of gas every time you say their names. my 73 got 6 mpg.

It would be cool to hear what kind of progress you make with your fuel mileage as you work on that thing. Good luck.

 

I'm with you on this one

 

I quote... myself?

That's a saving (or payback) of 10 cents per mile using the example above.

 

Agreed, although I somehow missed your post the first time.

 

Hah! That was my thread! Mileage ROI: Ratio change, tires or hedders?

Some other notes from the quest for mileage:
1973 Camper Special and needing better MPG
EFI options on a FE

There has also been some discussion about lock-up torque converters and overdrive units for the C6 (GearVendors, Doug Nash, et al) MSD ignitions, magnets (how do they work? lol ) electric cooling fans... but there really is no replacement for proper tune-up. I was making 8-9mpg on my truck and I picked up a whopping 2mpg by simply giving the old girl a good tune up. New everything... plugs, wires, Pertronix I w/FlameThrower coil, paper air filter, oil change with synthetics in the axle and trans, quality dino oil in the engine, new 195 Stewart/EMP thermostat, coolant change and fixing a myriad of serious vacuum leaks. I still need to check the timing, but I'm tempted to not screw with it because its been running so well! Next step for me is going to be installing a wideband o2 sensor left over from another project. I want to see how this thing burns while its still dressed up in all its factory parts I have an old MSD 6A in the garage I want to try out, see if it makes any difference in AFR or mileage (doubtful, but who knows?) Get the basics taken care of and go from there!

Remember, 2mpg in my case was a 20% INCREASE in fuel economy!