I have a 72 ¾ ton with a 390 2 barrel with C6 that has served me well. I did an easy overhaul at 140K – rings, mains and rods all went back standard. The truck still performs well but burns a little oil. I am starting to worry about the transmission – leaks a little and seems a bit tired – it is the original and now has 260K miles with only normal service – never been rebuilt.

Between sticker shock ( I paid $3300 for this truck new and thought I was getting screwed!) and a real dislike for the smurf truck style and all the plastic and thinner metal of the new trucks, I have decided to repower my 72. I do a lot of towing, and the 390 has always had enough power for me, but the gas mileage keeps dropping, likely because of the gas we get nowdays. I average about 8, and will drop to 6 when towing.

My question is which is better, rebuild the stock setup, or replace with a 460? And if a 460 is used, should I go with a naturally aspirated (carb) or with fuel injection? I know nothing about fuel injection – or the electronic controls used on the later engines. Will going with a computer controlled engine that has fuel injection be worthwhile? Can you do fuel injection without computer control? Do you get more power and better economy with computer controls?

Any thoughts on this subject?

 

if the 390 has served you well and you can work on it with out too much trouble, that is what i would go with. the fuel injected 460 might do a little better on gas, and mabey a little better on highway pulling, but if it breaks down away from home are you going to be able to fix it beside the road?

it mainly boils down to what "you" want to put in it.

 

Have u tried putting a different carb on ur 390. There is actually a formula to help figure out what *cfm* one should use.. I will dig it up and let u know.

 

I woul say a rebuild for the motor and tranny would improve things quite a bit for you, I dont think a 460 is going to get better mileage even if it was fuel injected, but I say go with what you know if the 390 and C-6 have been faithful thus far, then thats what I would go with.

 

Willie, I suggest that you pull both the engine & tranny and rebuild both. Likely it is using oil because you didn't drill it before and true up the bores.

Drill the engine 30 over and put a RV cam in and get ready for 500,000. Your gears might be a little lower than you really need holding you to the lower mpg. You should be able to hit around 12.

You can spend the money for 4 barrels, headers an the like, but me thinks a good two barrel will deliver just as good. IMHO

John

 

jowilker, I pull the snot out of engines from time to time, but almost never exceed 3,000 RPM - something my dad taught me when I was a kid. A big engine turning slow will give you lots of power and will last forever. Performance parts give you more power, but only at higher RPMs.

I agree, a 4 barrel and headers will not do any better than the stock setup - in the 1800 to 3,000 RPM range I operate in, and a high rise manifold will actually cost you power at lower engine RPM. If I stay with the 390 I will keep it stock.

I have to admit I expected a ringing endorsement for the fuel injected 460 - which has not been forthcoming.

 

> Can you do fuel injection without computer control?

Generally speaking, not in gas engines.

> Do you get more power and better economy with computer controls?

yes and yes

re:460
The Ford 460 is a great engine, just expect 8 mpg gallon, city, highway, towing, coasting down hill, in a van, in a 2x4, in a 4x4, etc. You will not see much of an improvement over the 390 in mpg.

You do not drive enough per year to make up any fuel savings by replacing it with a different motor swap (260000/32 years = 8125 miles per year)

re: fuel injection
You will be sorely frustrated the 1st time it breaks down and discover you need a TFI module, or crankshaft sensor, or MAP sensor, and the store does not have it, and it costs more then the whole ign. system on your 390. Or your in the tank fuel pump quit and besides the $140 your truck is disabled until you drain and drop the entire tank. Been there, done that!

I know and repair Ford EEC-IV, EEC-V and OBDII systems and even Chevy, Dodge, VWs and Hondas time to time. I have my own computer scanner and I can tell you I find my 1971 Ford 390 with points a much more reliable system where I do not want to walk home from the middle of nowhere from lack of a sensor that costs more then my entire electrical/ign. system on the 390.

I keep a set of points, condensor, coil, cap/rotor, and plugs (cost under $50) in my truck and the tools to change them.

It is almost impossible to to carry every sensor that can disable a EFI vehicle with you without spending a bundle. Some of the more common ones I use to carry (TFI modules), but, some are impossible to predict ahead of time such as a cam positioning sensor or the CPU itself (a rare occurance in a Ford, unlike a late 80s Chevy). How about being broken down somewhere because your coolant temperature sensor failed, the fan did not turn on, and the truck overheated. I hate when that happens!

If you need better gas mileage and yours is dropping, check out your fan, it might be part of the problem and a flex fan might save some gas.

 

Lots of ideas about what works and doesn't work on 390's, but here's my 2 cents worth. I pull a medium sized boat up and down hills to my favorite "honey hole". Before rebuild I had to hit 3rd gear on some of those steeper ones. Now I keep it in 4th on the way up. New mods was RV cam, Holley 600 rejetted, Edelbrock mani, Flowmasters, elec fuel pump, fatty plug wires, Pertronix, RamAir, etc. Also upgraded valves, gaskets, rings, new valve train. Also was lucky enough to find 390 block and crank that hadn't been rebuilt, so it was .30 over and cleanup on crank. Would have done mine, but it was already .60 over. Spent a little extra at machine shop for some of those "extra" things.

 

Thanks guys – I think I sort of forgot the KISS principal – have to keep it simple so I can keep it running. Like rebocardo said, I don’t want to be broke down in the Nevada wilds with a fuel injection system.

The truck has been mostly parked the last 10 years, since I quit farming and got a city job. It has been a good friend – outlasted two wives and several girl friends. I intended to get a new one when I retired, but just can’t bring myself to pay the price. For what they charge for sales tax and first year license plates here I can completely rebuild it.

I am also guilty of not doing my homework before I posted – I found the FE forum today and there is a lot I can do to the 390 if I want to keep up with fast traffic over the mountains while pulling my camper.

Without your advice I would have bid on a 460/C6 that is on E-bay – and hated the results.

 

There are a few cars that have been fuel injected w/o a computer. Some old Corvettes from the fifties and Alfa Romeos throughout the seventies. But this is based on old diesel mechanical pump technology. I'm certainly not suggesting it.

Recently, Horsepower TV did an FE build up. (Actually it was probably an old episode reaired recently.) I found it very inspiring because they didn't mess with the bolt on nitrous or anything too outrageous. They said that they were going to treat an old engine to some old basic technology. This of course centered around flat-top pistons that got 9.5:1 with Edelbrock heads. That and an Edelbrock manifold, a little hotter cam and timing set, a mallory ignition...

I've been considering going with this formula sans heads as those would be around $1200, and I would take some time to clean up a set of cast-irons. That and some headers in front of a good flowing exhaust would probably get you some good power and mileage (meaning double digits, 10 or 11 :-) but a lot of power.

The guy on Trucks! has done some bolt on fuel injections. This is a bit more expensive than a nice manifold and carb combo, but would pay off a lot on trucks with a lot of that pre-fuel injection pollution control like smog pumps and carbs that have 27 vacuum lines going to it. Apparently a lot of these are smog legal.

If you're interested, I reviewed the FE build up episode with the Tivo remote and laptop an took very careful notes on their formula. I've even started to price some of the stuff they suggested. I've you're interested, I'll email you some of the notes I've found. It's really not much more than a basic rebuild except for the heads.

I've been considering approacing this in stages. My problem is that I put on professionally rebuilt heads which dropped an intake valve seat shortly after installation. So I replaced the head, but now I have three chewed up piston tops. So I was thinking of going with the short block and maybe heads first, then maybe heads if I don't do them first, then ignition, then intake and carb, then aluminum W/P...

My truck isn't pretty and is stricly for business, but I figure here I can put money into the engine, and if I ever need to off it, then I can sell it more as an engine and not so much a truck. I might even get an offer from a T-bird owner.

 

WillyB,
I Have a 70 F-250 with a 360 and it sucked gas down and that old 2 brl kept having float troubles so I order the Edelbrock performer intake (not the RPM) and a matching 750cfm 4 brl carb. It solved my float valve woes and gets better gas mileage too! was getting like 7mpg with the old 2 brl and factory intake...now gets 12 mpg with the 4 brl and nem intake so I would go with what you have but upgrade to that setup

 

Thanks, Hotrod - sounds like you have a good idea. The problem with me and 4 brls is that I like the sound of the back two opening up - I swear it is addictive. I would be standing on it all day long.

And Alfetta, please send those notes - there is always something I can pick up on. I am still too new to be allowed to send emails, maybe you could send me one?

Thanks