I'm very Old, but very new here, for a bit of background I'm a mechanic and a Ford guy from way back, at the moment I have a 69 stang, and 70 stang,a 46 pickup, a 65 pickup, and the newest addition to the fleet is a 74 F-350

I'd like to tap your brains on the 74. It's a 460, C-6 2wd at present, but I am totally up for suggestions. I put on a lot of miles and with the present gasoline dilema I would like to try and achive something better than 8mpg with it.

It is going to replace my 90 E-350 which is also a 460 but Fuel injected and a C-6 with 4.56 gears that achieves 8mpg hyway or city

Right now I was thinking I would go with a 4 speed and the 90 FI engine out of the van, and couple it to a 3.55 rearend.

Any input would be appreciated.

 

If you can handle the computers and sensors for the EFI engine and the 3.55 gears go for it. The gearing will throw off the puter tho.

 

I just got done dealing with the same problem. I have a 75 Supercab with 460/C6 that was getting 8 mpg also. I rebuilt the engine and put a 5 speed manual(NV 4500) behind mine using an Advance Adapters kit and I get 18 highway with it but alot of money and work to put it in. I think the easiest most cost effective way is to put a E4OD behind the 460 thats already in it. You can get the electronic control for the tranny from Baumann engineering or scarf one from the junk yard. You can also put a Gear Vendors behind the C6 and have 6 forward speeds but the mileage will not be as good as the E4OD cause you've still got the non lockup C6 there which wastes a good bit of gas. Good luck from one oldie to another.

 

Whats your rears? and what is the OD ratio your getting with the 5 speed?

 

The OD ratio is .73 to 1 and the rear is a Dana 60 3.73. I want to mention that my 460 and everything on it is new which helps with the mileage also. The timing is set at 14 BTDC/stock Duraspark/regular diameter tires. My own opinion is the big difference in mileage is not so much that the 5 speed is so good but that the C6 eats up alot a gas which does not contribute to forward movement. To tell you the truth I was shocked to be seeing that I could get 18 with the thing. I only expected about 15 at best. Going back to a stick took a little getting used to after 20 years without shifting. My only complaint is I cant keep a cup of coffee in my right hand now-gotta put it down to shift.

 

Anything that involves the computer has to be exact to it.
Trans,rear end,fuel delivery,weightof vehicle,etc.

I am slightly confused with a statement though.

This one (the underlined part):

It is going to replace my 90 E-350 which is also a 460 but Fuel injected and a C-6 with 4.56 gears that achieves 8mpg hyway or city

Then with this comment:
Right now I was thinking I would go with a 4 speed and the 90 FI engine out of the van, and couple it to a 3.55 rearend.

My suggestion:
Replace the 460 with a 400 put a Edelbrock performer intake & a 4bbl edelbrock carb on it.
Plus, Replace the rear gears with 2.75's.

Then read my post in the FAQ thread about what affects fuel economy.

I thought you were asking about changes to the 74 ?

 

The gearing will not throw the computer off. It is not an electronic transmission. A 1990 model is still probably a speed density engine in a truck/van. It will make the speedometer off, but you could put a different gear on the speedo cable in the trans to fix the ratio change.

 

Ive got a 1996 f-350 4x4 with a 460 EFI engine and 5 speed OD trans with 3:55s and stock 235-85-16 tires....best ever hiway (empty) was about 16....at 55mph summer weather...its pretty amazing what these can do if you dont put you foot to it every chance you get....then its ez to go to about 10mpg. Its HARD to go 55 though...it has a sweet spot at 70....about 2000rpm

Im wondering if anybody knows how to get the kind of seat of the pants power that my old '86 F-250 4x4 carb'd 460 had.....and not screw the pooch on mileage.....this EFI is great...but it doesnt have anywhere near the gitty up the old one had.....NO...its not worn out....always been this way.

 

Holly Crap, your final drive is about 2.72. Not sure I can go that far without the OD, one of the uses of this truck is to tow my bobcat and possibly while full of sand. That's why I was thinking 3.55's. I met a guy over at Stangnet that has a 90 F-350 with a c-6 and 3.55's that tows a 30' fith wheel camper who claims he can get 14 towing if he keeps it at 55-60. I have no problem switching to the Stick, I never liked automatics anyway and towing seems to tear them up faster than normal. As far as the engine goes, the 460 I have just turned 80,000 and spent it's first 60,000 on propane before I changed it over to gasoline. It runs and acts like a brand new engine, doesn't smoke or or leak a drop of oil and has plenty of guts.

And to be perfectly honest I was hoping to achieve 12MPG, you guys just blew me away with your mileages.

Maybe I'll call my buddy at the Boneyard and see if he can locate a 5speed and the goodies to go with it.

Mil1ion; the E-350 donor does not have a computer controled tranny, it's a stock C-6 so I don't think it will effect the computer, and if the standard trans screws with it I can always find a 460 standard computer. I also have a friend that has a CHIP Burner, unfortuneatly he works on TV's so I'm not sure if he can figure out how to manipulate the CHIP in the truck, but he's always up for doing something off the cuff

 

Yes the final drive ratio is low, but in 4th gear it's still one to one the same as a C6 so you dont see the kinda gains Im experiencing unless your on the highway. But the beauty of the NV 4500 is it's still geared OK to tow 1st thru 4th. In your case there are 2 Dodge NV4500's you can get. I have the regular duty tranny but the other one is geared lower( its called the heavy duty) but still has the .73 final drive which would handle your big tow jobs but you use your 5th gear whenever you can. There is an article on the site for a NV 4500 swap and I have been intending to do one also but havent had the time. I want to mention with my truck I dont have any problem around town in 5th gear even as low as 35 mpg-no lugging. For those of you that know, I asked about how to submit an article and I got a reply to forward it to a email but the system blocked the email link so if anyone can tell me I'll get it done. Ive got all the pictures ready.

 

That sounds good, I just went and payed for the truck today, the 460 that is in it sounds very tight, I was surprised. It claims to have 36000 miles and it may be correct. I may stick with that engine if I can make the mileage acceptable. And you don't want to know what I payed for it

Any idea what dodges those trannies were in?

 

Let me clarify, right now my work truck is a 1990 E-350 460 FI C-6 with 4.56 rears.

I am trying to build a truck to replace it and hopefully get better gas mileage at the same time. I can either rape the E-350 or just sell it to build the new truck, doesnt' matter one way or the other.

The replacement truck I bought is a 74 F-350 with a 460 carb. and a C-6. I just went and payed for it today and checked it out. I'll know more about it after I get it home possibly tomorrow.

I wanted to get as much input as possible before I start cutting and stiching. There is no rush because teh E-350 if fine the way it is.

 

Okay thanks, that makes more sense to me

 

Gm also uses the transmission. GM 93-94 were built with a much lower 6.34 to 1.0 ratio but these can be hard to find. Current Dodge and GM NV 4500 have the same gearset that started in 95, but the NV 4500 that is put into the Dodge Cummins is extra stout and that is the gorilla of the NV 4500's. In my swap I didnt anticiapte that I would need new exhaust, carpeting and speedometer drive, plus transmission tunnel modification and driveline alterations. It turned out to be alot more work going from an auto to a stick than I thought. It definitely is not cheaper than going to a 4 speed automatic and is more complicated in many ways. Alot of the junkyard pedal assemblies and linkages are worn out and you need to buy new( thats why they call them junkyards I found out) which really runs up the expense. A good site that explains alot of this is High-Impact dot net. Being a former mechanic maybe you have access to a lift. Your gonna need it. I never could of done this job on my back. The NV 4500 weights 200 lbs so I got a $100 buck tranny jack from Harbor Freight which was indispensible plus I got a Bendpak lift which made the job doable for me.

 

I'm pretty well setup in the reconstruction end of it, I have a pretty decent shop with a milling machine and a lathe, as well as all the welding goodies to go with it, so fabrication isn't usually an issue. I can build adapter plates, mounts, crossmembers and rebush any old assy's I get so hopefully I can do it fairly cheap. I have a 4 speed out of a 69 F-250 that I can use for now, and see how it makes out with mileage. Don't know what the Rears are yet, I was suppose to pick it up today but lost the ramptruck so I'll be getting it tomorrow hopefully. If it has a decent set of gears in it I may just go with the 4speed and see how it does. I'd be exstatic with 13-14mpg so I'm not to hard to please