Fuel Economy 352 390

[410bruce]

Just curious, what are you guys with warmed up 390s or 352s getting for fuel mileage? Warmed up meaning a basic strong street runner--4v, mild camshaft, headers etc.
Is there a big difference between 390 and 352 mileage, all else being equal?

[hwoods]

when I had it in 1965--390 Galaxie 4:11 gears about 10 MPG

[frnkeore]

It depends on your weight, gears and foot, probably more than anything.

With 2.74 - 2.91, you could get as much as 18 mph (390), with a well tuned, low overlap engine, on the hwy. A little more with EFI.

Heavy accelerator pump use, brings it down, in town. Best mileage will be had using a vacuum gauge to know how to adjust your foot to get the best results.

Quench and chamber shape will help. The right A/F ratio combined with power valve setting, and especially EFI. One thing that will always help mileage, is a light car and high gears.

But, another way to look at it is, from the $ stand point. How much you spend, to get the highest mileage as opposed to how much the actual gas saved will cost. Money is money, weather it's spent in parts or gas. But, can you put a price on "fun"?

IMO, there is a lot to it, no matter what way you go.

[Gregg]

I have a '64 Galaxie with a 390, slightly upgraded cam, factory shorty cast iron headers, 2.5" exhaust, Magnaflow mufflers, C-6 with the lower 1st and second gear from a AOD, and 3.00 open rear gear.  Around town I get about 9 mpg.  I do like the sound so that includes a lot of WOT so I can chirp the rear tire on the 1 - 2 upshift.

[chilly460]

I rarely check it, but when I do I’m getting 17mpg highway with 4.10s and a Tremec 500.  Cam is 224/232 9.2:1 CR. 

[My427stang]

I ran my 71 F100 for years as a daily driver, .030 390, 9:1, 270H, Street Dominator, 600 Holley, headers, recurved distributor, 4 speed, 4x4, 3.70 gears, 33 inch tall tires.  Ran at 12.5 around town and 14.5 on a long run, ran great but wasn't knife-edge tuned back in the day. 

As Frank said lots of inputs, but, keep overlap low, compression high, mixture on the lean side for mileage. Tight quench helps the the lean mixture not ping, and then it's all how you drive it

My Mustang (4.89 EFI 4.11, TKO-600) gets about 15 on a good Nebraska back road trip, but I also tend to horse it now and then. It does well due to the gearing and EFI, certainly not built for mileage

[410bruce]

I'm impressed with the higher mileage you guys have posted, especially with the mods and heavy vehicles mentioned.
It stands to reason that if you're heavy footed the mileage will suffer but it sounds like if you drive around normal and like an old man, (at 55 I'm kinda there  ) 390s are capable of pretty respectable fuel economy.

Now, if you were to replace the 390 with a 352 in the above examples, would mileage go up or down?

[My427stang]

I'm impressed with the higher mileage you guys have posted, especially with the mods and heavy vehicles mentioned.
It stands to reason that if you're heavy footed the mileage will suffer but it sounds like if you drive around normal and like an old man, (at 55 I'm kinda there  ) 390s are capable of pretty respectable fuel economy.

Now, if you were to replace the 390 with a 352 in the above examples, would mileage go up or down?

In theory, up, but it depends how hard you had to work it to do the same job

[410bruce]

I'm impressed with the higher mileage you guys have posted, especially with the mods and heavy vehicles mentioned.
It stands to reason that if you're heavy footed the mileage will suffer but it sounds like if you drive around normal and like an old man, (at 55 I'm kinda there  ) 390s are capable of pretty respectable fuel economy.

Now, if you were to replace the 390 with a 352 in the above examples, would mileage go up or down?

In theory, up, but it depends how hard you had to work it to do the same job

Kind of what I was thinking as well, Ross.

Hoping some 352 guys will chime in here.

[Gaugster]

I was in the 9mph range even with a 2.75:1 out back but with lots of inefficiencies. C6 was slipping and barely made it through the season. Engines a little on the tired side. If my upgrade to the 6 speed auto goes well the fuel economy should improve some. Not hoping for miracles however. Just a higher cruising speed and more power handling. Current it's a 390 with an "RV" cam, Performer RPM, QF 680 cfm and an MSD ignition.

[frnkeore]

I had a '60 Ford, with a 300 hp, 352 with 3.54 gears and Cruise-O-Matic trans (4k lb car).  After I got drafted, in '65, I had to drive it to Fort Hood, TX, from SoCal. At 70+, I got about 16 mpg.

Now, if your talking PU, your hwy mileage will suffer, suffer even more with 4X4. I'd say take 1-2 MPG off for each, if you drive 70 mph.

[Royce]

I had a 74 F-350 with a car hauler ramp bed and a 360 4peed. 2bbl Autolite Fresh valve job small RV cam, 4:11 tall tires headers. Empty 13 maybe a 14 in there  Loaded.... 6-8

[shady]

'63 gal stone stock 352 auto 300 gears gets 12. No matter how I drive it. I think it should do better but...

[BB-63]

1963 Galaxie 390/C6 & 3:1 rear was 8mpg around town and 12mpg on the highway.  I think the C6 made it more thirsty than it should have been. 

[frnkeore]

The car I had, before the '60 Ford, was a '58 Edsel Corsair (heavy car, Merc Chassis, boxy, probably 4300), with a 410 MEL, it was a push button Cruise-O and had 2.91 gears. It got a  measured 16 mpg, on the fwy. I was really surprised. Maybe it was the leaded 100+ octane gas we had in those days

12+/1 CR was more the norm, back in the 60's and 70's for street or race builds.