6 banger mileage?

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lugnut1962

lugnut1962

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Hello, I'm thinking about buying a car with a good ol slant six for a daily driver. I found some old articles on the internet that says the 60's models were rated for around 30mpg. A buddy at work says a small six from this era won't get 20mpg at idle, down hill with the wind at my back?
Any of you slant six owners have any input?
Thanks....
 
I've never gotten better than 16 mpg's. I have no idea how others get 30+. I just don't believe it. Now, maybe when it was new or it is in GREAT condition.... that would be different.

Bottom line, enjoy it no matter what.
 
70 225 with 160K 16-18 mpg.
63 170 with 170K maybe a bit higher; gas gauge works so I'm not as concerned
 
I have a nearly stock 73 with a 225 /6. I get ~ 16 mpg around town and ~ 25 mpg on the road. The engine has nearly 300 k miles on it and it has never been opened. The carb was replaced with a reman that I later rebuilt. It is jetted with a 51 main jet. The deviation from stock is replacement of the stock exhaust manifold with one that has no heat provision for the carb and intake manifold. Rear gear is 2.76:1
 
69 Dart 225 bone stock,904,294 gears.I get an average of 21 mpg and it is a blast to drive.
 
I get around 25 mpg highway and around 20 city in my stripped down 72 4dr.
engine: bone stock 225 w/2 1/2" exhaust and 170k miles on it
trans: 4 speed od from a pickup truck
rear: 8 1/4 3.21 sure grip
body: sparce interior no carpet no back seat, manual steering, manual brakes, never wieghed it but i'm guessing right around 3000#
 
Ahhhhhh....Mannnnnn....the ford guy was right! The car I'm looking at is a 62 Lancer. Funky...but cool.
Hmmnmm....Thanks all!
 
well my old val got 16 to20 now my bros got it and tells me shes getting 35 i call bs if so some one better then me at math check it lol he we show up soon on this
 
daliant said:
I get around 25 mpg highway and around 20 city in my stripped down 72 4dr.
engine: bone stock 225 w/2 1/2" exhaust and 170k miles on it
trans: 4 speed od from a pickup truck
rear: 8 1/4 3.21 sure grip
body: sparce interior no carpet no back seat, manual steering, manual brakes, never wieghed it but i'm guessing right around 3000#
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standard or did you adapt an automatic to fit it? didn't know the trucks came 4 speed with OD thought they were 3 speed with OD
 
I rebuilt my 225, bored it .30 over and milled the head a little so I could get some moving a little easier and not be a slug at stop lights. I drove 110 miles on one tank of gas so how ever big the gas tank is divided by 110 is what I get with a stock and untouched 904.
 
J4R3D said:
I rebuilt my 225, bored it .30 over and milled the head a little so I could get some moving a little easier and not be a slug at stop lights. I drove 110 miles on one tank of gas so how ever big the gas tank is divided by 110 is what I get with a stock and untouched 904.
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If you're saying you get 7 mpg, you have something seriously wrong with your slant. Even if it's in a truck.
 
I can get INFINITY miles per gallon as long as I don't start my car or attempt to drive it!
 
This is a long time ago but my 68 valiant and 71 duster that were not properly tuned and maintained would get at least 25 mpg on the highway. I also drove at no more that 60 mph. A properly tuned and maintained slant should easily get 25 mpg on the highway cruising at 65 mph.
 
jkeck: That was back when a gallon of gas was just that and not 10% ethanol. ;)

All I can get around here is 80/10/10 gas/alcohol/water :p
 
J4R3D said:
I rebuilt my 225, bored it .30 over and milled the head a little so I could get some moving a little easier and not be a slug at stop lights. I drove 110 miles on one tank of gas so how ever big the gas tank is divided by 110 is what I get with a stock and untouched 904.
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thats very poor milage, you should be getting around 200+ miles to a tank of fuel
 
Getting 30MPG aint gonna happen. If you follow the good advice on here and slantsix.org you can get in the lower 20's.

I'm running a super six setup with the HEI mod and feather duster exhaust and I'm getting an average of 21.5mpg with about 60/40 highway to city driving.
 
ok I know this might be a really dumb question but would it matter what size Carb you have? I just got a 1965 dart for my son and we were wondering about gas milage. I told him as long as he is getting good grades I would buy him one tank of gas a week... after that it was up to him and his friends... he asked me what kind of gas milage it got and i told him it should be really good. but hell honestly i do not know.
its a charger 225 not that I think the "charger" means anything with a 1 brl carb. My brother got a rebuild kit for the carb and it fired right up. So i am seeing here just as an average 15-18 city if its in decient shape? but would the carb make a difference?
 
my friend and i cruise his '70 challenger convertible with an all original /6 225 and it gets 22mpg. i've never heard of 30mpg that sounds a little far fetched, but i think a solid 22-25mpg would be doable.
 
Mine gets 20 city 28 highway @80mph with 2.76 gears, 175,325 miles as of this morning...

Calculators say with a 25.3" tire (205/70/R14's), 68 mph puts me at 2,500 rpm. 81mph puts me at 3,000 rpm... Imagine the fuel economy I'd get if I had an overdrive gear...
 
DouglasMB said:
ok I know this might be a really dumb question but would it matter what size Carb you have? I just got a 1965 dart for my son and we were wondering about gas milage. I told him as long as he is getting good grades I would buy him one tank of gas a week... after that it was up to him and his friends... he asked me what kind of gas milage it got and i told him it should be really good. but hell honestly i do not know.
its a charger 225 not that I think the "charger" means anything with a 1 brl carb. My brother got a rebuild kit for the carb and it fired right up. So i am seeing here just as an average 15-18 city if its in decient shape? but would the carb make a difference?
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Yeah Carb matters but Carb condition matters more. Yours is most likely a 1bbl Holley 1920...which is a good carb as long as its not remanufactured.

The Charger means nothing. Dodge slant sixes had a "Charger 225" sticker and Plymouths had a "Super 225" sticker.

There are various things you can do to get it better mileage before spending a bunch of money. Tune the carb with a vacuum gauge to make sure you're pulling the most vacuum. Also do a valve adjustment because chances are its never been done or hasn't been done in a long time and the valves are tight. Check the timing and put it at 8* btdc or so as long as the engine doesn't ping. Readjust the idle to specs and have him drive it for a week and see what you get on the next fillup.
 
/6 Matt said:
Mine gets 20 city 28 highway @80mph with 2.76 gears, 175,325 miles as of this morning...

Calculators say with a 25.3" tire (205/70/R14's), 68 mph puts me at 2,500 rpm. 81mph puts me at 3,000 rpm... Imagine the fuel economy I'd get if I had an overdrive gear...
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I'm sorry but I gotta call bs on the 28 highway. You sure the pump didn't just click off too early on accident or something? 28 highway would put you in the top 1% of slant sixers in the world.
 
We just went to Long Beach, Washington and back last weekend, the 70 Duster we bought for my wife has a rebuilt slant with 26,000 miles on it, stock other than that.

Before we left I bought a brand new 1920 from Slant Six Dan.

Not sure how big the tank is, but Google says its 190 miles one way. I started with a hair over a half, and went from Lynnwood to Montesano and filled it at a hair over 1/4, that was 115 miles at 65-70 mph.

On the way back, I filled it in South Bend, and made it home with a little over a half tank, that seemed pretty good mileage to me.
 
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