I suppose this has all been hashed out but I'm new. I have a '92 F350 Crew 4 x 4 I use for towing a 26ft trailer with bikes and wood and family. I do some easy off-road on trails and dunes. 460 with auto, 35's and 4.10's. 123K on the odo. I am looking to make it work as good as it can because I can't afford a diesel and actually, I like the damn thing. Thinking Banks Power Pac or something less expensive but I hear nothing is as good, with 4.56's posi front and back. Does this sound right? Is there something I can do to improve on 6 mpg? Thanks for any suggestions.

 

Well you can try to change the O2 sensors to improve MPG's but these engines are not fuel sippers, my 460 now get 3.5 city and 5 HWY it used to get 4 city but I dont know what happened, all the ignition parts have been gone through, same to the FPR, but man does she move down the road even starting in 2nd she moves. To date i'v gone through universal joints, posi, brake master, clutch slave, water pump, fan, fan clutch, radiator..........and LOTS of gas ! It's only about $70-80 to fill up . 120 miles traveled, 35 gallons burned. Sorry for the long post and sorta off topic.

 

[QUOTE=1990F2504604x4my 460 now get 3.5 city and 5 HWY it used to get 4 city but I dont know what happened,[QUOTE]

That is horrible!

My 81 F350 crewcab, with a 460 and a CARB got double that.

Are you quoting mileage while hitched to 10,000 lbs, or is that empty/unloaded mileage quote?

 

Thats exactly what I was thinking. 3.5 in the city is horrid. 5 on the highway is even worse. I bet he can actually watch his fuel gauge drop if he lays on it.... I know u could in my dad's 70 torino with e 351C and 4 speed...

 

That mileage is all unloaded, and yes the needle does drop when floored if I pass (four lane road) as I go up this one hill to get home/work. She smells really rich too, I mean like a lawnmower rich, that smell you get when you just start it off the priming bulb. But like I said she has TONS of power and runs really good.

 

With that mialage you have something WRONG!

 

I thought that I had it bad. I get 10 unloaded in a perfectly stock truck which all goes to hell, of course, when I strap everything on. So, any other ideas?

 

I'd check your fuel pressure and then your regulator. With that thing burnin that much fuel, it should be smokin like a hyped up diesel!

 

3.5 MPG??????!!!!! Somethings wrong there, what is it if you keep your foot out of the gas all the time?

 

Well I think I found my problems! Got digging around the truck today and found a JET Performance chip in the thing ! Maybe thats why it pings sometimes and I can never time the thing right even with the SPOUT removed, oh and the O2 wire was burned/cut/melted off the sensor. It has never ever thrown a code and the bulb does work because it lights before starting.

 

Well that o2 sensor needs to be working, that's probably why your getting bad gas mileage. It doesn't always have to light the light, it may have come on when you didn't see it, but only certain codes will make the light come on and stay on. Other times it will come on and shut off, or never come on but store a code in the computer.

 

There are really only two things you can do to the 460's that are EFI, unless you stumble upon a Calif 460 that is mass air.

First, open up the exhaust. Free flowing cat and at least single 3.5" exhaust or dual 2.5". The 3.5" gives 9.6 sq inches of area and the dual 2.5" gives 9.8". I wouldn't go bigger than single 4" (12.56 sq inches) or dual 3" (14.14 sq inches). Even those might be pushing it for low end torque. My truck had dual 2" for an area of 6.28 so I increased it by 50%. Trust me, this is correct (area = pi(3.14157)*radius*radius). My F250(see sig) was getting between 11-12 mpg until I just took exahust off and replaced with one off of a 97 Powerstroke. Last trip I got 210 miles on back tank and it was still running, so ~13mpg. That was the only mod I made, but I did remove the kitty box but a free flowing one is recommended. And much more power. She'll break the rearend lose now idling in 3rd gear at about 10-15mpg. The only way to break the rearend lose before was basically a clutch drop from a standstill.

Next, you can work on the intake. You can imagine that if the engine is turning at 2400 RPM at 60MPH, you are sucking in 7700 cubic feet of air (this is basically a 20 ft by 50' by 8' tall building of air) per mile. The restrictions in the formed hoses, etc are killing the intake. Either buy or make a cold air intake system. I am planning on using bendable exhaust pipe and route each side to the appropriate side of the radiator and use a cone filter and build a box to cover the bottom so it doesn't get splashed with water/mud/you name it.

Now, this will only help if you have a good tune-up done. Do not use platinum plugs, splitfires, etc...use a good plain sparkplug like Champion Truck Plug or something like that. Good 8mm or 9mm wires and correct timing. With a auto you might get up to 8mpg to 10mpg depending on overdrive ratio. Your 35 tires are killing you alittle, but for the cost of gears ($2000) that'll still buy close to 700 gallons of gas. I always add up the cost of mods and figure out how much gas I can buy with it and how long that would last me. I only put about 2000 mi a yr on my truck, so it has to have a quick pay back for me to do it.

Good luck.

 

Perfect 460?
I have a 90 f350 4x4 running 33 4.56's crew flatbed (read really heavy).Bought it used, has a paxton supercharger and empty cat. Originally was getting a best of 13 hwy average 11.
Supercharger rebuilt with a bigger impeller and added the banks system. Wow pulls real hard. Mileage still the same.
Recently added MSD6 helped to smooth the lower RPMs.
Pulling a New 30 toybox with a buggy ,quad, and 3quads in the truck plus the kitchen sink. I’ll get about 6-7 mpg. If I’m in a hurry (70+), that drops to 3-4.
Still would like a little more power, but current setup is working. Currently would like to fine tune, fuel pressure/plug gap/timming.
Good luck.

 

I had a 460 in my '79 bronco. It was mildly built, plenty of power. I had a 600 cfm carb on it. It got 9-11 mpg with 4.56 gears and 39.5 tires. Perfect 460??...I doubt it. But it was a lot of fun seeing the looks on the yuppys' faces as they'd try to pass me on the right at stop lights in their BMW's.

 

Handyman , the gas gauge was droppin because the front end of the car was probably a foot off the ground. After third gear the gas probably came back! On the injected 460's, can you change the heads for DOVE heads? Mileage probably would be a little better because power would be better also. More power , less pedal?