Hello all,
I just acquired an '83 F-250, 460 with C6 & 4x4. I need to unleash its potential, as well as mileage if possible.

What are some popular modifications/upgrades, & has anyone tried any aftermarket EFI and seen results worthy of the cost? I'm shooting for maximum HP and mileage.

Thanks

 

I don't have a 460 and haven't worked on them, although several on here have. But, from what I've read the only reasonable way to get mileage on these trucks is to get the RPM down. I'm guessing that you have 3.50 gears which, with the C6, means you are turning ~2800 RPM at a true 60 MPH. The 460 puts out more torque than you would ever need to pull that truck at 1700 RPM - or less. So, you need some kind of overdrive.

Said another way, you can play all the cam/carb/EFI/exhaust games you want, but all you will succeed in doing is to get more power, not MPG. While that can be satisfying in and of itself, it won't help much with the mileage.

 

Raising the compression ratio will help power and mileage, but if you have to put more expensive gas in it, that won't help much. The overdrive tranny would be your best solution. Look at all the newer trucks, they all have overdrive transmissions in them.

 

Heres a good read, the story is on an EFI truck though.

FOUR WHEELER Magazine's Project M.P.G.

 

Unfortunately....the only thing I can do about milage on mine is drive my focus as my DD.

I agree with Gary though on the gearing. Mine will shift into 3rd at about 25 MPH (well most of the time, that's another story) and it has tons of torque to pull away from there.

Have to look at it from a return on investment statndpoint too. There are several FI systems for it...so even it you gained a couple MPG...it would take a long time to pay for the FI system.

A person I work with was trying to convince me to trade my focus for a prius. I would get about 10 additional MPG which I calculated to save me about $450 a year. Well the payment on a prius would be that much more a month than my focus.

 

Thank you all for your input. I have asked about the overdrive options with a local salvage yard. I have not received a reply yet.

My rig turns about 22-2300 RPM at 55. 65-70 MPH is obscene, so what overdrive option is available for my '83 F-250 4x4 with a C6 auto trans?

 

--A GV OD usable only in 2wd, $3000+

--A E4OD automatic, with stand-alone controller, probably about $3000 if you get a reman'd box + the $500 controller

--Switch to a manual trans use the ZF 5 speed, figure $500-1000 for a box plus the parts and labor, maybe $1500-2000 by the time you are done.

Nothing is going to make much difference that engine/vehicle combo.

Figure you get a 20% increase in fuel economy. 20% of 10 mpg gets you to 12 mpg. Will that pay for any OD option in the life of the vehicle?

 

Assuming 30" tires & 3.54 axles?..........so depending on your intended use for the truck, you could re-gear to lower your rpm at higher roadspeeds - e.g. 3.0:1 axle gearing would drop about 400 rpm @ 70mph.

It's a compromise, but with a woken-up 460/C6 combo it would still be practical, unless you are wanting to do heavy towing.

 

Any idea what you are getting for mileage right now? When is the last time it has had a "basic tune-up?"

 

Around here a ZF5 goes for about $500, and I got the 460's clutch, flywheel, and pressure plate with it for that price. But, you will want to replace the clutch disk to have a new one. You will need a new starter, I believe, and will need the clutch pedal and linkage from a manual truck. I think it can easily be done for $1K, and since the 460 came with a ZF5 in the later years it is pretty much a bolt-in swap.

But, as Ken points out, changing the rear axle gearing is less expensive, although somewhat less effective. The problem is that it leaves you with the C6 which is inefficient, at least partly due to the torque convertor. There are mileage-type convertors out there, but they won't give you the efficiencies of a manual transmission.

 

I have no issues converting to a manual trans. It's preferred, as long as it will work with my transfer case.

As far as cost vs. when it will get "paid" for, as long as this truck runs, I have no need of a new one at the ridiculous cost of $50k. I restore antique vehicles, and this truck looks good and only had 88k on it, so I think it deserves a "pick-me-up"

Thank you all.

 

P.S. I do agree with shying away from expensive and/or exotic modifications; however I did buy the truck to tow a flat bed car hauler for the antiques. I towed a 91 Cherokee the other night and it seemed the rig had a difficult time & mpg went right out the window.

I also agree it needs a tune-up, perhaps a pair of reman 429 heads, manifold and a different carb. It has an Edelbrock, which I've beret really been fond of.

If I don't convert to EFI, what's the best carb option?

 

I meant "never" been fond of. Sticky auto-correct...

 

I'm told that the transfer cases that Ford used swap from tranny to tranny. But, you will have to get a 4x4 version of the ZF5, which is what I got but failed to say. In fact, include in the list of parts the BW1356 t-case that came with all those other parts for $500.

But, the ZF5 came behind three different engines: 302/351W; 460; and diesel. And, since those have different tranny bolt patterns make sure you get the 460 version.

Also, those came with hydraulic clutch assemblies. You can use that on our trucks, but your firewall will almost for sure crack at some point. There is a stiffener bracket available after-market that bolts to the inside of the firewall and prevents this. Do some searching on this forum for that information as well as other tips on the ZF swap.

And, the reason I know this is that I'm in the middle of a similar swap to Dad's truck. Fortunately the 460 bolt pattern is the same as the 351M in the truck. Unfortunately the flywheel size as well as spacing from the block is completely different, so it isn't bolt-in as it is on the 460.

 

Them's fighting words! You'll find things polarized on here re carbs. Some, like me, are anthing-but-Holley lovers. Then there are those who love Holleys, and that includes Bill Vose, who used to run a carb and ignition shop so has lots more credentials that I do. One user, lavatan, has an E'brock on his 460 and seems to like it. You might ask him about his experience.

So, mileage went right out the window? From what to what? Maybe you have a problem.