Alright guys, I just picked up a donor engine and trans from a '94 F-150 4wd: 5.8L MAF engine w/ E40D transmission. Just trying to get a pulse on how you guys feel your 5.8s perform in the heavier trucks (MPGs for daily driving, light to moderate towing, etc). The recipient of this donor setup could possibly be my '71 F-250 crew cab 4x4 in my sig. If I can't squeak some low double digit MPGs outta the 390/C6 I might go ahead with this swap to get a slightly more economical powerplant and the OD.

Stats on the 71 (current):
FE390 w/ Edelbrock hi-rise intake and 4bbl Holley, C6 w/ married NP205 xfer case, Dana 60s front & rear w/ 4.10 gears, shackle flip & 4" lift leaf springs f/r, 315/75/R16 BFG MTs.

(Future plans):
Swap a good running Quadrajet carb I'm currently running on my '69 Bronco on in place of the POS Holley, replace the 4" lift springs with stock packs I got from a '69 F-250 4x4 donor on all 4 corners, replace wheels and tires with some stock aluminum wheels from a '97 F-250 wrapped in 285/75/R16 Goodyear Dura Tracs. Hopefully these mods will get me to a liveable economy for Daily Driving. The towing that this rig will see should be pretty easy. At max I'd say 12K combined weight of my 68 Bronco crawler + trailer. Mostly just DD duty haulin' kids & the frequent light to moderate load in the bed. If I still can't keep shoes on my kid's feet AND gas in the tank then I'm lookin' at "plan B" which is the 5.8L EFI/ E40D swap.

Haven't gotten much response in the bumpside forum so figured I'd try here as more of "us" on this forum run this setup. I know the 6BT swap is out there but initial cost of the components for that kindof elevate it out of the budget with as much as those engines/ trannies are bringing right now...

Thanks for any responses/ insight/ experience you guys can give.
Fungus

 

I would think that just taking things back to stock would help considerably, you've got a fair amount of rotating weight there. While I love the 351 in my 89 F250, it's significantly under powered in stock form, you'd be looking at putting headers on it at the very least, possibly cam, to get the same performance out of it that you're getting from the 390, not to mention the fuel economy that you're looking for. The 4 speed would help more, if there's a way to bolt it up.

 

That's the problem with the 390, there's really no economical way to mate up an OD tranny whether it's auto or manual. If the 5.8 goes in I'll go through it and freshen it up w/ new bearings, rings, seals, etc. Probably put a good cam in it, possibly heads & definately headers but the OD tranny would be the best part of it all.

Also, I'm building a 5.8 now for my 68 Bronco project & just finished a 5.0 for the 69 Bronco that's just waiting to be swapped in so most of the components would match all 3 rigs and make spare parts easy to shelve plus my familiarity with all of it.

Thanks for the reply!

 

You would still keep the the 351w EFI correct? If so, then with the OD transmission, and a little bit of improvement to the engine like a good aggressive cam and headers, you would definitely be ahead for MPG, but if you put different heads on the motor and freshen it up a little besides, you will definitely have a better overall motor than the 390.
The 351w will perform well in about every task you put it to. They are good pulling motors, not terrible MPG in stock form, and they have plenty of torque to move big tires around on mud trucks and rock crawlers. The nice thing about the 351 is that it's a small block so it doesn't have to move a truck and the weight of a big block like a 460 and 7.3 does. With that in mind, I always prefer the screaming small block over the big block, especially because the 351w has SOOO many aftermarket parts.
That is a really nice looking truck by the way!

 

Yeah, would DEFINATELY keep the EFI on it. Both the SBs I'm going to run in the Broncos are EFI so I'm familiar with the upgrade in older rigs. I'm sure I could find a set of GT40 heads to throw on it as well fairly cost effectively. I've got a set of C9 351W heads but haven't done the research on whether or not those would be an improvement on the stock heads of the F4TE block, prolly not enough to justify a rebuild on'em and swap'em out.

As far as weight, this rig has had a D60 kingpin swapped underneath the front and is really overkill for what this rig will see. I'm always keepin' my eye out for a late '70s D44 HD w/ discs to roll under it. That would definately shed a couple more pounds off'er.

Thanks for the props. She's in pretty good shape. I've picked up quite a few parts for it and am anxious to get the time on our next visit to get some of'em on!

 

351w is the way to go, i got a 390 in one of my trucks and it isnt that great. simple cam, heads and headers with a good tune should put u in the neighborhood of say 300hpish or more and about 400lb-ft or more along with about say 15mpg with stock sixed tires and proper gearing, maybe more than that. like gnr22 said theres so many aftermarket parts for a 351w its unreal, and you can always stroke it up to 427 if you want more power out of it and throw supercharger on it too haha

 

Yeah I hear ya. Going big with one though would obviously blow any MPG gains but certainly a possibility.

Putting the topend on one out here this afternoon as a matter of fact for my 68 Bronco project. '94 F4TE block, stock crank/ rods/ pistons, Comp 35-308-8 5.0 roller cam, Scorpion 1.6 roller rockers, Edelbrock performers w/ 2.02/1.60 valves, Lightning lower intake/ Cobra upper, 65mm TB, 70mm MAF & 24#ers. Should do real well in a little Bronco! Easy to find nice parts for and still affordable.

 

I have a '97 F350 4x4 with the 351W. It does anything I ask it to. I haul, plow, and tow.

I don't know if the '91s had them by then, but mine has a roller.

you can achieve high teens with it easily. I got 18-20 empty once or twice at 55mph.

 

That's an awesome bump. Everyone's got an opinion, but I believe I would keep that bump all HD if it were mine. Keep the D60, go big block (keep the 390 or go 460) and drive one of your lighter, small block rigs when you want to save some fuel.

 

The OD trans will make a big difference in milage when cruising at steady speeds but that's a heavy vehicle so you won't see much improvement in stop and go traffic with any powertrain combo.

 

I agree. The main benefit would be for highway cruizin'. About the only thing I see giving better econo in town would be a diesel swap & that is substantially more cost up front for the donor vic and not sure the gains would really be worth it with the assinine price of diesel!

 

What did you do to achieve those types of mpg's? I have a 1997 f250hd with a freshly rebuilt 351 and I can only get up 14 if I'm lucky.

 

well simple upgrades to your truck can get you those numbers, idk if his truck is stock thought but i hope i could get those numbers one day

 

Very cool old truck
I swapped in the 5.8 into my '90 F250 last summer.While it was a noticeable difference in power, it still wasn't what I was expecting it to be. I can climb grades in 5th gear while lugging the engine that the 5.0 would have needed 4th gear to climb up. MPG's are about 12-14 highway, probably 8-10 in heavy stop and go traffic.

I have the dual down pipes from a +8500 GVW F350 that go into a 'Y' just before the cat, other than that, everything is stock. 3.55 gears, 265/75/16 General Grabber AT's, 5 speed manual gear box.

 

beautiful truck..learning alot about my truck form these older threads

"the 351w will perform well in about every task you put it to. They are good pulling motors, not terrible MPG in stock form, and they have plenty of torque to move big tires around on mud trucks and rock crawlers. The nice thing about the 351 is that it's a small block so it doesn't have to move a truck and the weight of a big block like a 460 and 7.3 does." GNR22