Fuel Efficient Build---352 or 351W

[oldiron.fe]

                                                                                                                                                             I worked for a construction company in the early 70s and had several crews to keep track of and each supervisor could order a new pickup of choice. I ordered a (as I remember a heavy 1/2 I think upgraded load)   the motor i got was 390 w/auto not sure of gas mileage seemed to be very good and  had good power so good with load capacity it got borrowed for some long hauls for different equipment I think it was 2bbl with higher rear gear(2wh drive) ---maby the motor was running in a good rpm torque zone most of the time or just a good combination -bore/stroke and torque-- over time 390 stroke helped mileage/power over 332/352--410 may be better for heavy p/u --for p/u and a light work 390 always seemed to do well -2bbl or small 4bbl seemed to do best on fuel-- put a brick under foot seems to help most!!! and keep in good torque zone build for good low rpm work   

[410bruce]

Well, a little different turn of events here.
Made a deal for a 1998 2wd Explorer 5.0 and will be using the entire powertrain from it. The engine runs great and idles smooth, however it does have 170,000 miles on it.
It does move forward and back under its own power but as far as running through all the forward gears, that is undetermined at this point.
Pretty excited about this. GT40 style intake manifold, GT40P heads, coil pack ignition system and a small, pea-shooter cam. Should be a nice, torquie, smooth running package for the truck with decent MPG, I would think.

[machoneman]

Good score. At a minimum, I'd yank the timing chain/gears and replace them. Also, the valve seals if not a valve job too. 

[TJ]

 I think you said you have a C6 tranny now so I imagine you'll like the 4R70W a little better.  I'd be less excited about the  '98 vintage sbf when considering the amount of work for the whole swap...I'm guessing the power and mpg will be only a little better than the current I6.  A coyote 5.0 would definitely be more exciting. 

[410bruce]

Good score. At a minimum, I'd yank the timing chain/gears and replace them. Also, the valve seals if not a valve job too.

When I come across an engine with miles on it but still runs well, I generally do replace the timing chain set and oil pump and pick-up.
Won't pull the heads. If I do that, then it snowballs from there. lol.

[410bruce]

I think you said you have a C6 tranny now so I imagine you'll like the 4R70W a little better.  I'd be less excited about the  '98 vintage sbf when considering the amount of work for the whole swap...I'm guessing the power and mpg will be only a little better than the current I6.  A coyote 5.0 would definitely be more exciting.

No more work than anything else, really.
Yes, a Coyote would be more exciting. It would be exciting to have the money to purchase everything I would need for the Coyote swap as well.
Not going to find a Coyote engine, transmission and all the wiring and fueling to swap into my truck for a grand--which is what I am paying for the entire Explorer. Disc brake rear axle I believe there too, if I care to use it. 

[machoneman]

Good score. At a minimum, I'd yank the timing chain/gears and replace them. Also, the valve seals if not a valve job too.

When I come across an engine with miles on it but still runs well, I generally do replace the timing chain set and oil pump and pick-up.
Won't pull the heads. If I do that, then it snowballs from there. lol.

True on the 'snowball' effect! Still, I'd replace the valve seals with the heads still on. Why? I see tons of high mileage 5.0's in all kinds of passenger cars that smoke out the exhaust in acceleration, deceleration or (!) both. They harden with age and start passing oil....as you likely know. Cheap, a tad difficult but worthwhile.

[TimeWarpF100]

Okay guys, another fuel economy question for you regarding a couple engines.
If you had your choice, which engine would be a better candidate for a fuel-efficient build, a 352 or 351 Windsor?
Given the current situation around us now has me thinking more about MPG than HP.
Would still like to have good torque and a throttle responsive engine, only focus more on efficiency.
Factory cylinder heads, pump gas, backed by a C6 in a 4000lb truck. Will be using an aftermarket throttle body EFI system.
I do have one of those overdrive Top Loaders that came in late '70s trucks I could install, if it would be worth the trouble.

As always, any input greatly appreciated.

My best MPG FE is a current truck (F100 Ranger '66) with a stock 352 and a factory Overdrive and 3.25 gearing. Consistent 22 mpg @ 65 MPH
where as a typical 352 with a 3.50 gear or a F250 with 4.10 & taller tire is 10-12 mpg. Factory 2v carb always the best. Tried other 2v's and lost 3 mpg.

Another daily 352 truck that has a added 1961 4v intake and holley and fine tuned with as much timing as I can give it is 14.5 mpg if I drive it nice but now the holley is giving issues so mpg recently dropped under 10.

I have found as typical the manual trans always seems to give better mpg.

For fun of it I wanted to see what I could get out of a 390 with low rpm power and MPG main goals. Started off with a .020 390 block and custom pistons with better ring pack, 9.00 comp, idle to 4000 rpm custom cam and will be running a c-6 with a GV OD and a 3.50 gear set to start off with. I have a few extra 3 spd overdrive (factory type) transmissions I may try. Goal is 18 mpg @ 65 mph. For this one I had Drew do me up a 390 GT Holley and I added 406 manifolds from Kugal. Excited to see where it's at for power and mpg but thinking may not quite get to 300 hp but should make incredible tq.

Truck I drive the most I did a 2020 Raptor Crate engine and a 10spd auto with a 3.50 gear but switching to a 3.0. It gets 25 mpg @ 65 on 91 and 20 mpg on E50 while making over 600 hp to tire and 658 tq to tire. If I get too happy with throttle it drops to 17.

The factory 3 spd manual OD trans are a great deal for mpg. I have found the GV OD is also a great improvement.

Did one 351w and was not impressed with mpg or power.

Sound funny to say FE and MPG in same sentence but the stock 352 with a tall gear and od shocked me as to what was avail from factory 56 yrs ago.

[410bruce]

Okay guys, another fuel economy question for you regarding a couple engines.
If you had your choice, which engine would be a better candidate for a fuel-efficient build, a 352 or 351 Windsor?
Given the current situation around us now has me thinking more about MPG than HP.
Would still like to have good torque and a throttle responsive engine, only focus more on efficiency.
Factory cylinder heads, pump gas, backed by a C6 in a 4000lb truck. Will be using an aftermarket throttle body EFI system.
I do have one of those overdrive Top Loaders that came in late '70s trucks I could install, if it would be worth the trouble.

As always, any input greatly appreciated.

My best MPG FE is a current truck (F100 Ranger '66) with a stock 352 and a factory Overdrive and 3.25 gearing. Consistent 22 mpg @ 65 MPH
where as a typical 352 with a 3.50 gear or a F250 with 4.10 & taller tire is 10-12 mpg. Factory 2v carb always the best. Tried other 2v's and lost 3 mpg.

Another daily 352 truck that has a added 1961 4v intake and holley and fine tuned with as much timing as I can give it is 14.5 mpg if I drive it nice but now the holley is giving issues so mpg recently dropped under 10.

I have found as typical the manual trans always seems to give better mpg.

For fun of it I wanted to see what I could get out of a 390 with low rpm power and MPG main goals. Started off with a .020 390 block and custom pistons with better ring pack, 9.00 comp, idle to 4000 rpm custom cam and will be running a c-6 with a GV OD and a 3.50 gear set to start off with. I have a few extra 3 spd overdrive (factory type) transmissions I may try. Goal is 18 mpg @ 65 mph. For this one I had Drew do me up a 390 GT Holley and I added 406 manifolds from Kugal. Excited to see where it's at for power and mpg but thinking may not quite get to 300 hp but should make incredible tq.

Truck I drive the most I did a 2020 Raptor Crate engine and a 10spd auto with a 3.50 gear but switching to a 3.0. It gets 25 mpg @ 65 on 91 and 20 mpg on E50 while making over 600 hp to tire and 658 tq to tire. If I get too happy with throttle it drops to 17.

The factory 3 spd manual OD trans are a great deal for mpg. I have found the GV OD is also a great improvement.

Did one 351w and was not impressed with mpg or power.

Sound funny to say FE and MPG in same sentence but the stock 352 with a tall gear and od shocked me as to what was avail from factory 56 yrs ago.

Good information, thank you.
That first 352 is indeed impressive. On the second 352 truck, what transmission and rear gear were you running?

On the 351 Windsor, you're not the first person I've heard who says it doesn't get good mileage. They come with some pretty poor cylinder heads designed for the 302, and they are even stifling for that engine.
I wonder if it's a case that the heads just don't flow and consequently, you need to lay into the throttle more to get it to do what you want. Or maybe most of them found their way into F-250s and were just overwhelmed with tonnage?

Since the deal with the Explorer didn't materialize, you have me taking a look at the 352 again. 

[TimeWarpF100]

2nd truck which is my daily driver now and the truck I am building a clone of the one my dad bought new.

It has the Factory 3 spd Column OD trans in it but I have yet to hook up the wiring to activate the OverDrive. This truck has a 3.50 gear
MPG had started to drop off then found the points had started to burn at 5000 miles. Will probably switch to DuraSpark MSD combo.