Small block mileage

-
D

dave ellis

Well-Known Member
Joined
Dec 30, 2012
Messages
378
Reaction score
74
Location
jacksonville, florida
The 318 has never been known for good mileage. All else being the same what is the real difference between the mileage potential on the 318 and the 360?
 
What's good mileage .. ?? I'm asking because of all the older small blocks I've owned, the 318 has been probably more efficient than the other brands. Like 289's, 302's, 283's... I've owned and driven them all.
  • 318 2bbls on the highway have got 24-25 mpg easily in the 3-OD cars, and most can get 21-22 otherwise in smaller cars.
  • The difference between 318's and 360's?? In heavier vehicles or bulldog nose vehicles, sometimes the 360 actually can do better.
  • We've taken a C-body on vacation with a 360 and averaged about 17 mpg rollin' 65-70 mph.
  • Our '77 full time 4x4 Ramcharger got 13.5 mpg on our 4k mile vacation cruis'n 60. Our '77 Short Van B100 with the 318 2bbl average the exact same. We hoped we changed that with our mods to the van, we'll see.
 
Last edited:
dave ellis said:
The 318 has never been known for good mileage. All else being the same what is the real difference between the mileage potential on the 318 and the 360?
Click to expand...
THEY'RE NOT??? REALLY??

I can show you B body bone stock 318's back in the day that got 18-20 routinely

I swapped a 71 high compression low miles 340 into my 70RR--which had been a 440-6, so heavy 4 speed and HP robbing Dana 60 with 3.54 gears and it got over 17 WITHOUT being careful
 
yeah, seriously- if you're not getting minimum high teens with a stockish 318, there's something seriously wrong with your motor. A 360 won't help matters any.
 
Last edited:
My '69 Swinger 418, Sixpack, 4-speed with 3:55's and 255/60/15's driving easy at mostly 50, sometimes 55 will get 17mpg.
 
Some years back, the Wifey and I took a '70 Dodge truck on a 2k mile trip. I had a 340 in it with a TQ, MP cam, headers, 2.02 J heads, backed by a 727. I put 2.76's in the back and got 16-17 mpg on the trip. In a truck @ 65 mph (that was the speed limit then). I lowered the metering rods on the TQ, boy could a guy get MPG with a TQ
 
My 67 dart 273 2bbl gets 12.5 mpg on the interstate.

My 1986 jeep with a 318 and electronic everything 15 to 17 on the interstate
 
It’s not a fair comparison:
Modern v6 Chrysler -300hp and 28mph
Old style v8 LA 318 140hp and 14-18 mph

difference: computer designed engine and electronics vs Venturi suction device.
 
Syleng1 said:
It’s not a fair comparison:
Modern v6 Chrysler -300hp and 28mph
Old style v8 LA 318 140hp and 14-18 mph

difference: computer designed engine and electronics vs Venturi suction device.
Click to expand...
My 318 will definitely do better than 18 mph even if I'm dragging an anchor... :)
 
73 D250, 360 2-bbl with 340 A-body dual exhaust,727, 4.10's with 30" dia. rear tires. IF I stayed at the posted speed limit of 55, it would get 17 on the highway.
 
I had a 74 Duster with a 318 2 barrel, 72 340 exhaust manifolds with dual exhaust to the rear bumper that got 23 mpg on the highway. My 70 Challenger 340 used to get 20 mpg on the highway, but I had swapped 2.76 gears into it because I had a year of road tripping to do between Asheville, NC and Clarksville, TN. My 71 Challenger conv with a 360/727 and 3.23 Sure Grip got 20 mpg on a trip to FL and back a few years ago. The convertible really surprised me doing that well. It has a MP cam, LD340 with an Edelbrock 600 and 70 340 HP manifolds with 2 1/2 inch exhaust.
 
Of all the 2000’s and older from Chevette to Crown Vic never saw much difference in all of them, I get 15-16 mpg in town some a few mpg less and some a few more.

My Dodge Avenger is probably the best I’ve driven 22-23 mpg in town.

I wouldn’t worry about it.
Similar performance is gonna eat about the same amount of gas no matter the engine size.

Is it a summer toy that get only a few thousand miles on a year? If so a couple of mpg ain’t gonna make that much $$$ difference anyways.

Plus a car will take a certain amount of hp to move it down the road which will take basically a certain amount of fuel in a narrow range, different engines might be slightly more efficient than others doing it.
 
dave ellis said:
The 318 has never been known for good mileage. All else being the same what is the real difference between the mileage potential on the 318 and the 360?
Click to expand...
318s get easy mid twenties gas mileage.
Careful tuning will get you more.
360's are a hair behind, one could argue about a 8 mpg diff, based on heads n stroke.
Are we talking pre big rod motors or ?
The early 318 'light rod' might get a c hair more mpg's. Jmo
 
We will now get 200 examples from members, whose ex-girlfriend's Aunt Patty got XYZ mileage. No examples of controlled testing....
While I have no actual numbers, I can think of a reason for the OPs statement: stroke. Lack of it. And that would be why a 360 gets as good or better mileage...& more HP as a bonus.
 
Bewy said:
We will now get 200 examples from members, whose ex-girlfriend's Aunt Patty got XYZ mileage. No examples of controlled testing....
While I have no actual numbers, I can think of a reason for the OPs statement: stroke. Lack of it. And that would be why a 360 gets as good or better mileage...& more HP as a bonus.
Click to expand...
Examples may or tend to be exaggerations, however they can also be real world numbers.
 
seems like a little bit of . . . . . just a little

pinochio.jpg
 
dave ellis said:
The 318 has never been known for good mileage. All else being the same what is the real difference between the mileage potential on the 318 and the 360?
Click to expand...
2-3 mpg worse.

However! I did manage 20 out of my 360. It was a ‘79-360 in a Magnum, with a OEM 4bbl intake, 600 cfm Edelbrock, MSD 6, dual exhaust off of the manifolds, a 904 & 2.76 gears on 26 inch tires.

A 318 is good for another 2-3 mpg’s in a lighter vehicle.
The Magnum weighed in at 4,000 with me and a gas tank filled.
 
dave ellis said:
The 318 has never been known for good mileage. All else being the same what is the real difference between the mileage potential on the 318 and the 360?
Click to expand...

Disagree with this. 318's I have had all got decent gas mileage. The stock 360's however have all been gas hogs.
 
My 66 273-4 barrel 4 speed get's 18+ hwy. My 70 318-2-barrel automatic gets 18+ hwy. A overdrive on either would gain 3 or 4. Even a lock up on the 70 would gain a couple. Both cars have 3.23 gear and tall tires.
 
What fresh hell have I awoken? Haven't had a 318 in many years, but we drove our cars differently when gas was $0.39 a gallon. Yes, on that freaking old. Anyway, I appreciate all the info. Was just trying to decide what motor to put in an a body to get the best mileage and still have enough grunt for when I go up into the Rockies.
 
You must log in or register to reply here.
-

Back
Top