Fuel economy question...

[Triplegreen500]

OK, so yes - I am aware that "if you're worried about fuel economy, you need a new hobby". This isn't a "damn, my Charger sucks at fuel mileage!" thread - it's more a question for the group about state-of-tune.

I track the mileage (MPG) in all my vehicles as a matter of course. Not because I hyper-mile or anything like that (my size 14's are too heavy for that!)...but, like tracking my heart rate during workouts, it's a great indicator of mechanical problems and a dip in mileage for no apparent reason, makes me look at the vehicle to find out what's wrong...and fix it before any type of catastrophic failure.

That said, I'm getting enough miles on my Charger that I'm pretty confident that this is "what it gets" for MPG. 70 Charger, bone stock 318 2bbl, factory air cleaner (single snorkel), factory manifolds, dual exhaust. 904 automatic, 2.73 rear. Close-to-corret size tires - speedo reads 65, GPS on Waze shows an actual speed of 62. She's getting me a pretty consistent 13 mpg, country/mountain driving and highway driving combined. No racing - it's a cruiser, not a bracket machine - just...cruisin' around in the car I've wanted all my life.

So, for the others around - does 13 sound about right? She runs great, no flat spots, no hesitation, no stink of stupid-rich exhaust, good acceleration, no pinging, no lugging. Rolls freely, no brake drag, no bearing resistance. Or, does it sound low and I should start looking at state-of-tune stuff?

I'm not looking to turn this into a 20mpg car - that's not what this is about. Just...setting the baseline for "healthy MPG". If this is where it's happy...it is my baseline, and I go from here, no problem. But if people with a similar setup ARE getting 20mpg...I'll start digging and tuning. Healthy cars are happy cars!

 

[Jerry Hall]

I don't have a running 318 car, but a 70 Charger is a heavy car. Unless you have a heavy foot I think 13 is low. I get a little over 12 in one of my 67 Hemi 4-speed GTX'S. The Hemi automatic car is in the 11 bracket. That is not playing with the second 4bbl. I mix my fuel in these cars for 95-100 octane. Regular gas in 1970 was 89 octane most places. Today's fuel is crap but I think your car would be good with the mid grade fuel. There are to many variables to say what you should be getting. IMO I would be looking for 16+ mpg with everything 95-100% on your car. I don't expect much gas mileage out of my Hemi and 440 cars as I like to play a little and sometimes get a heavy foot. 74 years old and still a kid when I drive my old iron, the best time machine a guy can own.

 

[33 IMP]

Ive been driving for a lot of years, and i have never had a car that got good, let alone great, mileage.
I hear some claims for what some guys say they get, and i just mentally walk away.... cause i hate to call a guy a liar to his face.
I think 13 is a little low, but somebody is gonna claim he gets 22. Or 26. Or......

 

[Runcharger]

Yeah: Someone will reply you should be getting 47MPG any second. I think it is a touch off as well. I would expect around 15. If it is running well though as it sounds like it is, I probably wouldn't worry about it. How do the plugs look? If they look decent I would maybe ensure the advance curve in the distributor is optimized.

 

[steve340]

13 mpg is quite high consumption for a stock 318 engine IMO.
I am pretty sure my stock 440 in my GTX is doing better than 13 mpg.
Ethanol blend fuel will be consumed at a higher rate than straight gasoline.
As Jerry Hall said - heavy car/small engine so that is for sure a factor.
A good tune could not hurt.

 

[turbine68rt]

In addition to agreeing with previous posts, the power to weight ratio, combined with a 2.73 rear may also be a factor. Fwiw Out of curiosity while heading out to Ohio for the nats I decided to check mileage. With a stock 440, 727, & 3.23 I got 17mpg. This was all steady highway driving. City....different story.

 

[Bob Sawyer]

I know it's not a 318, but back in the day - 1980, I drove my '68 Charger R/T, 440/4 spd. 3:54 Dana from Princeton, WVA to Indianapolis for the Street Machine Nationals. I got a consistent 17 mpg there and back.
I was right proud of that.
Around town, not so much.

 

[Mackman]

I had a number of Mopars back in the day set up similar to yours. Generally they ran 15-17mpg.

 

[Nate S]

As stated above, seems a bit low, I’d expect 15-16. Setup sounds correct though. In my experience, in cars set up well like this, the single thing that kills mileage the most (yet still leaves clean plugs and a good running car) is timing and more so vacuum advance issues.

I had a ‘70 Coronet R/T with 440-4sp that got 8, yes 8 mpg with a Mallory dual point (no vac advance), and 12 with a factory electronic vac advance distributor. Ran super both ways. Almost no difference in driveability.

 

[Triplegreen500]

Great input everyone, thank you. I was also expecting 15ish...I'll take a look at timing. Plugs read clean and I've already been through the carb, fixing float issues (it was too low, starving the engine at WOT).

 

[Big Bad Dad]

Back many years ago when my 67 R/T was my daily driver, I checked and was getting about 9MPG. This was with the old dual point distributor. 440/4 speed with 3.54 Dana. I now have converted to electronic ignition. But dont check the mileage, 'cause I dont care... LOL

 

[747mopar]

Sounds high to me as well, I would expect somewhere between 15-20 out of a 318 of coarse that's flat freeway driving.

Ive been driving for a lot of years, and i have never had a car that got good, let alone great, mileage.
I hear some claims for what some guys say they get, and i just mentally walk away.... cause i hate to call a guy a liar to his face.
I think 13 is a little low, but somebody is gonna claim he gets 22. Or 26. Or......

With overdrive maybe?

 

[Bob Sawyer]

Back many years ago when my 67 R/T was my daily driver, I checked and was getting about 9MPG. This was with the old dual point distributor. 440/4 speed with 3.54 Dana. I now have converted to electronic ignition. But dont check the mileage, 'cause I dont care... LOL

Did you make it to the Williamson Rd. cruise last night in Roanoke?

 

[F4R/T]

Your fuel quality maybe affecting your mileage corn gas does take a lot more to make the efficiency of straight gas. Also you may consider bumping your timing up a tad and recurve the Distrubutor would probably help. My 72 charger was a 318/904/2:76 car and 3 guys, a crap load of supplies and a big cooler was getting 19 going to mopar Nats consistently ... around town 14-15mpg. I’d check the tune and fuel. Good luck !

 

[69 Sleeper Bee]

My 69 Coronet with 383 auto 3.23 rear gets 11 to 13 mpg average.

 

[66Satellite47]

My '76 Dodge cargo van weighed about 4600#, I guess more than a '70 Charger 318. My 318 van regularly got about 14 sometimes 15 if very softly driven on the freeway. IIRC my dads '68 Fury III 318 got around 15 maybe 16.

 

[Kern Dog]

70 Charger, bone stock 318 2bbl, factory air cleaner (single snorkel), factory manifolds, dual exhaust. 904 automatic, 2.73 rear.

2.76. The 2.73 was a Chevy ratio.
My red car was equipped the same when I bought it. I got 16 when I drove freeway.

I got almost 13 from my car with this 440/493 with the 3.91 gear and a .78 Gear Vendors. That was a 3.05 final drive.

 

[Slap Stick]

You said mountain cruising. At what altitude do you live?
I bet your carb needs to be rejetted for the altitude. And as altitude goes up octane requirements go down.

 

[toolmanmike]

Although a Charger is a bigger car, it should get better than low teens especially with that rear gear. My 70 Swinger with the stock 318-2 barrel gets a solid 18 if I drive it nice. You should get 16 or more if you keep the cruise rpm at or below 2000.

 

[YY1]

@tripplegreen500

My 73 satellite 61,000 mile 318 with 2.73 8.25 gets real world average 14.5 MPG.

Almost bone stock 2 barrel with a partial open element air cleaner, timing at book spec 0 degrees, and dual 2" exhaust.

My car is a stripper so likely weighs less than yours (3700# without me, but with a spare, jack and speaker box in the trunk).

I say you are in the ballpark