21 mpg?!?

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kittypancake

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I've been using my well worn, 109k mile, oil leaking, oil burning, tranny slipping 72 Valiant as my main vehicle until the wife's car is repaired. I've been keeping track of the mpg. SHOCKED that it gets 21 mpg in its less than stellar tune!...not unhappy, just shocked.
 
I used to daily drive a '74 Valiant, and if I kept my foot out of it, I could get high-teens for mileage. It was a fairly stock 318 with a new cam, carb, and exhaust on it, but the bottom end and heads were untouched. With the right driving style, it's amazing how well these cars can do.
 
I've had a couple 318 2.94 66/67 Coronets that got 20.
 
I did a mileage test in my Duster 340/4 speed and it did 19 MPG (even with hammering it a couple times & opening the 4 BBLS).
When I had my '79 Volare with slant 6, I used to get 28 highway and 22-24 city.
 
Last Highway trip I did with my Dart, I punched in the figures on one of those on ine mileage calculators... First it said "I must have a hole in my gas Tank" as it came back with

12 MPG! on the Highway!!!
 
My first car was a 66 Slant 6 no option Coronet. It would get 25 mpg on long trips back in the day of 75 mph speeds. It had over 200k miles. Modifications included taller air cleaner, water injection, and CDI ignition I developed from scratch.

I sold it to buy my 66 273 Baarracuda, it has auto and ps. It still got 25 mpg. Now days low 20s. My experience suggests about 10% less mpg with 10% ethanol.
 
DemonK9 said:
I did a mileage test in my Duster 340/4 speed and it did 19 MPG (even with hammering it a couple times & opening the 4 BBLS).
When I had my '79 Volare with slant 6, I used to get 28 highway and 22-24 city.
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Was that with a 833 O/D or with a 904?? If with a 904 I'm just gonna get the aspen that I bought last night running and drive it!! My 89 s10 with a 2.8 non O/D 5 speed only gets 22-23 highway!!
 
With my 67 Ranchero with a 289 I was getting around 18-20mpg. I haven't tested the mpg in the Dart with the sl6 since it has been in varying states of work since we got it. Pretty sure the mileage is decent though. Needed gas when we bought it and I put about $40 in the tank (around 9 gallons I think) and we put on a lot of miles before I had to fill it.
 
I kept careful records in my 69 Dart w/ 225 slant and got a consistent 21.5 mpg highway. That was with a Holley 1920 which usually idled rough. That was 1977 - 1990 mostly before they started putting ethanol in the gas, which loses ~5% mileage.
 
I'm wondering what kinda mileage improvement I will get with an alignment.?
 
my eddy headed, m1 single plane, 383 dart, with a 4500 stall and 4.10 gears gets about 6mpg. ha ha ha
 
i drive 14 miles a day and but about 15 bucks every other day in it so premium is 3.89 which turns out to be i have no idea mpg speedo doesnt work
 
3700 lb 73 Satellite bone stock 318-2 (with duals) 2.76 rear 904 gets 13.9 in mixed driving.
58,000 miles on motor.

4200 lb 00 Dakota CC 5.9 with cat back duals and K&N filter w/o/d (3.9/2.7) gets 14.1.
139,000 miles on motor.
 
tunnel rammed 340 dart gets 14mpg combined -and thats with a little punishment here and there,3.23 gears,904,2500 stall.if you drive it with a light foot it gets around 16mpg maybe better if you drive the speed limit on the highway.i had a 73 valiant with a warmed up 318/904 combo with 2.76 gears isky rv cam,4bbl,dual exhaust.it got around 20mpg on the highway.wife 66 valiant slant six 2bbl gets about 18 combined city/highway.
 
YY1 said:
3700 lb 73 Satellite bone stock 318-2 (with duals) 2.76 rear 904 gets 13.9 in mixed driving.
58,000 miles on motor.

4200 lb 00 Dakota CC 5.9 with cat back duals and K&N filter w/o/d (3.9/2.7) gets 14.1.
139,000 miles on motor.
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That is odd, my last slant 225, 3 on the tree, 3.91 was in a 71 D-100 running 275-50-15 front tires and 295-50-15 rear gave 14.5 mpg, tank after tank, year after year.
The milage would dip down a little in the winter.

You would think after 30 years Chrysler could make a truck that got better milage.

FYI I loved my old 03 Suzuki DRZ 400 street / trail bike that I bought new, it would average 73.4 mpg...But the trade off was every oil change at 3K miles you had to put a new set of tires on it.
 
my 68 dart with its original and tired slanty and an OD 833 gets 16 ....I have never seen more than 16MPG in the year and a half I have had it.
 
RaniDart70 said:
my 68 dart with its original and tired slanty and an OD 833 gets 16 ....I have never seen more than 16MPG in the year and a half I have had it.
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That is decent MPG for a tired motor, what gear?
I know my first duster with a 318 got worse gas mpg with a od than a straight 4-speed 3.23 gear.
 
I get about 13 mpg. In my 383 valiant 389 gears. My 87 crown Vic still get 20 mpg with over 200 thousand on it...
 
sireland67 said:
That is decent MPG for a tired motor, what gear?
I know my first duster with a 318 got worse gas mpg with a od than a straight 4-speed 3.23 gear.
Click to expand...


2.76 ...it was originally a 904 but I changed it to an OD to have the manual shift ....with a gear that shallow it takes off pretty weak with the manual, but once its on the highway up to speed then it rides really comfortable.
 
I just checked mine after a 200 mile highway trip. 17.6 mpg.
HP273/4/speed 3:23 gear. Wonder if a O/D would get it over 20?
 
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