Redhawk.... mine is a 71 highboy 4spd and the 460 in question is a 76 2wd camper special.

Bear are you talking like a ram air feed? I have been wondering about one of those. My 1970 gto had ram air and at highway speed it seemed to get a little better mileage when using it.....

 

> get better mileage than a 390

Not likely, when I think 460, all I think about is 8 mpg no matter what you do and no matter what vehicle it is in, truck, car, or van.

One big plus about a 460 is there are tons of aftermarket doodads and toys for it. I never knew what a FE was until I bought my 1971, but, I kind of like it now :-)

I think any carb 460 is going to be a dog until you ditch the factory carb and stuff. Even the ones that had the factory/police ether injection. Serious lag. The EFI 460 in the newer vans have pep though.

If you need 400+ horsepower, start with the 460. If you just want some go pedal, I would stick with the 390 and the better mileage. I just put a Holley Street Avenger (4160c?) on my worn out 390 2 BBL manifold with an adapter and picked up 2 mpg extra!

 

well dont know what to tell you thats what i got driving from Bozeman, Mt. to Anaheim Calif. on my last trip. try using 15.5 AFR late model lean burn setup, W/ water injection. for long distance driving. it works!

 

Well I think you all know my thoughts on the Monster 460.....I like both my 460 stroker for what its being build for..a 390 wont touch it.... And for what my 70F250 needs to do..the 396ci...and the mild build I have done with the C6 and the TransGo kit....and Locker Dana 60...It all works just fine..

I almost did the engine swap....and decided against it....for what I would be asking the truck to do...A nice rumble street cruiser....and very trust worthy..Drive it anywhere type truck,and look good doing it!!

But if I had a truck that allready had the 460 in it..or a 4 wheel drive....I would do the swap in a heart beat!!

No matter what I have done to my 390..It gets 10MPG...No matter what!! Even towing....and that with a 3:73 gear...

I am Guesstimating 5 or 6 with the 460/521" stroker... And thats only because the induction system is a Ported Offy T-Ram and 2 Holley 850's on top...

Russ

 

Well my needs are for towing lots and daily driving. The truck is being used as a courier service to gas lease sites and highway driving. I live in the mountains and that is also where the work is. Lots of hills to climb. I also use it to camp and hunt so the 4x4 is used lots too. And when time permits I want to play in the mud!!!!!!!!!!
That is why I was building the 390 up..... or swap to 460 and build it instead.

See it is a tough call because I really like both engines.

Think I'll go fishing for the week, drink a few wobblies and decide next week....

 

I'm too lazy to quote, so here goes:

You can build a 390 for well above 400hp if you know what you're doing. Shoot, that's where mine is! (ok, slightly above 400hp according to DD2k, but who's counting?)

My 390 gets 15mpg on the highway, about 12 in town. This is with the fuel injection mind you. But it is possible, and I'd think a WELL TUNED carburetor could come close to matching it. And I have a heavy foot. Once I get the electronic ignition on it I expect those numbers to increase.

I had a friend with a 460 in a truck. 10mpg highway, 6-7mpg in town. BEST. And it was stock.

Whatever you build, remember, mileage (theoretically) goes up disproportionally with compression, so build it up for high compression and the mileage will follow, so long as it doesn't ping.

 

Yeah I was gonna use 360 pistons to get the 9.5:1 you recomended. You must really have that thing dialed in well because as strong as mine is I can only get 11-12 highway trying to squeeze mileage out. Mind you a 2bbl and a heavy foot in town doesn't help much. Or the awesome factory exhaust manifolds!I think the build you and I originally came up with will work the best.

'Shoot, that's where mine is!' ??? SHOOT??? lol

 

Sorry, a little redneck-ism getting in there. I am from Iowa after all.

Edit: On the mileage, what compression are you running? Also, you might try leaning out the carb, adding a little timing, inflating the tires to 35psi, and so on.

 

Aw schucks man, that there darn carb ain't fit fer da birds!

The motor is still all stock. EVERYTHING.... I had to put the build on the back burner for a couple weeks so I haven't even started yet. We're buying a new house and something always bites me in the butt so I am keeping extra cash just until that's finalized. I run 4.10's with 35's at near max pressure. Timing is around 10 degrees.
To do anything to that carb I need a sledgehammer, 3 sticks of dynamite, and 300 rounds for a 50BMG. Autolites are junk....

 

Aha! The 4.10's are what's getting ya. I run 3.50's.

 

I was considering going to the junkyard and pulling the front and rear axles from a 90's model 1 ton and modify the perches and drive shafts to fit and install a proportioning valve. I'd have discs on the front then too. I think 3.73's would be a good alternative. That way I still have bottom end but a little better highway gear too!

 

Trust me, with the motor built like mine is, you still have PLENTY of bottom end with the 3.50's. But if you want to go 3.70's, it's your mileage.

 

Well I have got 3:73's in mine and at 65mph its about 2700 to 2800 on the Tach...

But I am also running 16.5x 12.50x 33" BFG's too...

Russ