Very impressed with gas mileage

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toolmanmike said:
Those Magnums are pretty efficient. (the 318's anyway) 2 barrel or 4 barrel? Most times the 4 barrels will get a tick better mileage if you keep your foot out of it. All depending on carbs of course.
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It had a 650 cfm AFB when I did the trip. It has a Quickfuel 600 vacuum secondary on it now, but I haven’t done a big trip like that since.
 
One of the big variables is the fuel level at the end of the fill. Using the same pump each time helps minimize the differences but there are still differences. In general one ought not to draw a definative conclusion out of one fill.

None of that has anything to do with your practical joking buddies which of course is a whole other variable. LOL
 
You can't use the word "average" to describe a one time mileage check. But if it get's XX miles per gallon when tested that way it is capable of getting that mileage. Just not averaged over hundreds of miles. Watch your late model cars mileage meter when you are going down a hill. 99.9 but that's not an average.
 
I believe the OP … If my 68 Barracuda can get 16 with a 360 and a 222/229 .550 lift cam I think 28 with a well tuned slant in a lighter car is totally possible ! Whats up with all the negativity on FABO lately ? As soon as I read the thread title I knew this would happen .
 
mbaird said:
I believe the OP … If my 68 Barracuda can get 16 with a 360 and a 222/229 .550 lift cam I think 28 with a well tuned slant in a lighter car is totally possible ! Whats up with all the negativity on FABO lately ? As soon as I read the thread title I knew this would happen .
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It's the world we live in now. Sad and very frustrating trying to herd cats!
 
pearljam724 said:
What planet are you living on ? My average miles per gallon that particular trip was 27.8 miles per gallon. There are no exceptions or variables for that particular trip. That is how it works. Based on your philosophy. People can’t estimate fuel mileage accurately until a vehicle has 200k miles and is being crushed. I simply stated that I traveled 156 miles and that miles per gallon is a very good indication what the fuel mileage is for my car. Would other trips consume better or worst average miles per gallon ? Absolutely, more or less by a few miles per gallon
at the most. If you’re dissecting my outcome. To be honest the car is actually a little more economical than that outcome. As I traveled this trip over mountainous terrain. A lot of drifting. However, as much drifting as I did on this trip. I climbed just as many hills as I drifted down. And I took the same exact route returning. I’m willing to bet, if I were to travel a less mountainous route. I could easily hit 30 mpg traveling the same distance. I’m 47 years old, I know exactly how mpg variables come into play and I also understand more miles calculated would be a better indication. If any of you are calling me a liar. I’ll bet any of you, any amount of money. I can prove time and time again to average a minimum of 25 mpg regardless the circumstances.
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You tell him kiddo!
 
I've had /6s that got great mileage, and others that drank gas.
I've had 318s that were the same way. Often in a car "just like the last one I had" but somehow the 2nd rendition was never as good as the 1st.
My dad had a 76 feather duster (early build before 1/1/76, it was a 3 spd instead of the 833OD and still had SBP and 4 wheel drums)
That car and my mom's 79 lebaron "super 6" were the best (of many) /6s for mileage we had.
My 79 d100 wasnt bad for a /6 in a truck.
All the rest were about the same mileage wise as the many 318s we had....
 
pearljam724 said:
72 Scamp with a slant 6 with 60k original miles. I just returned from a 200 mile trip with that Scamp and averaged 28 miles per gallon !!!
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1. Was your 200-mile trip all downhill with a tailwind?
2. Have you checked the accuracy of your odometer?
 
crewchief said:
28 mpg would be nice, but my '73 340 w/ 2.71 gears, ps, pb, a/c getting 10 mpg...I have no complaints. Love all that power.
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Something wrong there!

Best mileage V8 I had was a ‘79-360/904/2.76 in a Dodge Magnum sporting 235/60/15’s on all 4 corners. I gave the engine dual exhaust off of the exhaust manifolds @ 2-1/4 w/an H pipe, a factory 4bbl w/a 600 AFB and a vacuum advance distributor from the junk yard off a truck that I just stabbed in and ran w/a Chrome box.

The reward was a solid 20 mpg’s up and down I-95 multiple times to and from NYC & ether Richmond Va. or Atlanta Ga.
mbaird said:
Whats the best mpg you ever got out of a /6?
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17 mpg’s, and I got roasted big time here by every slant six guy (and a few others) for not knowing how to tune a 270,000 oil leaking, rocker clunking, dog leg driving ‘71 Scamp with a 225, rear gear unknown.
 
MopaR&D said:
Did you verify your speedometer reading was correct with GPS? If that was reading high it would have given false odometer readings as well. Also how did you measure fuel consumptio
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TF360 said:
2.76 gear most likely, and I bet the tires are a little taller than stock. Sounds reasonable to me. Non A/C car? Power Steering?
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MopaR&D said:
Did you verify your speedometer reading was correct with GPS? If that was reading high it would have given false odometer readings as well. Also how did you measure fuel consumption?
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I verified the speedometer and odometer reading this evening. Speed is 4mph faster than gps and odometer is dead on mileage wise. And that’s all that matters. So my calculation was spot on.
 
TF360 said:
2.76 gear most likely, and I bet the tires are a little taller than stock. Sounds reasonable to me. Non A/C car? Power Steering?
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215/70/14 front and back. No AC / no power steering and manual drum brakes front and back. Points ignition. 38 pounds of air front and back. Timing set at 10 degrees advanced.
 
The 1976 Feather Duster and Dart Sport Lite with /6 and 833OD were the first American cars to be rated at 31 mpg hwy. Not the Vega or Pinto. /6 Mopars!
I got 17 mpg city over about 4000 miles in my 1987 D150 SWB /6 833OD 3.91
I just put a 2.93 SG in my 72 Satellite 440/727 and drove 230 miles at 70 mph average on 14 gal= 16.43 mpg.
 
pearljam724 said:
I’m not exaggerating or telling tales. 27.8 miles per gallon averaging 60-70 mph. I would have not believed it myself had I not documented it. I traveled 78 miles and used 2.8 gallons each direction. I was assuming I would get 16-18 mpg. That’s why I documented everything to settle my curiosity.
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I have no reason to doubt. Very impressive.
 
One thing I have found over the years. Some cars that have low slung fuel tanks & low filler necks can get an airlock & give a 'false' full reading. You do get great MPG though! My current car is one of these & if I am doing a mileage test, I fill the tank with the car on a downhill slope.
 
run it till it sputters outta gas, pour in 1 gallion, run it till it sputters out again, true mpg is how far it went for it quit rolling the 2nd time!!
 
Verify the odometer againast a GPS. Suprisingly my odoometer is quite accurate. The speedometer is all over the place. My stock '68 225 with 145K has been a consistant 18.5 MPG in mixed driving after a real good tune up (valve lash, float level set,weights in distributor not stuck, vac advance works, heat riser not stuck, etc.).
 
SIX225 said:
Verify the odometer againast a GPS. Suprisingly my odoometer is quite accurate. The speedometer is all over the place. My stock '68 225 with 145K has been a consistant 18.5 MPG in mixed driving after a real good tune up (valve lash, float level set,weights in distributor not stuck, vac advance works, heat riser not stuck, etc.).
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Which matches what the vast majority of what others say
 
RustyRatRod said:
No, you cannot average ONE trip. It doesn't work that way. Go look at any window sticker. It states MPG as an average. That's always how it's been calculated. Go back and look at all the responses here. Mine was the one who called you a liar the LEAST and yet you go off on me? How bout screw you and the horse you rode in on? You just made the list.
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Relax, bud. You’re too uptight. It’s not that big of a deal. We are simply having a conversation. I disagree with your point. It’s not a personal attack on you.
SIX225 said:
Verify the odometer againast a GPS. Suprisingly my odoometer is quite accurate. The speedometer is all over the place. My stock '68 225 with 145K has been a consistant 18.5 MPG in mixed driving after a real good tune up (valve lash, float level set,weights in distributor not stuck, vac advance works, heat riser not stuck, etc.).
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I did. Same results as you regarding the cluster. Speedometer is 4 mph faster than gps and odometer is dead on down to the tenth of a mile compared to gps. Make no mistake mine gets mileage I stated. I’ve run the car all over hell’s creation since then. It sips gas. It’s shocking to myself having owned several LA small blocks in stock form.
 
Not sure if everyone tuned into his statement that he did a fair amount of "drifting" going down long mountain passes. Not saying it's cheating at all, but it does skew things a bit from how MPG might normally be tested. I personally test my average fuel mileage everyday on my 2010 commuter corolla, 155 miles/day total (hey, it's a boring drive). On the long downhill pass in the morning, I can coast over 7 miles and so my record is, I have averaged just a hair over 60 MPG on my morning commute! In the afternoon going home and UP that pass.....I will average right about 32 ~ 33. Oddly enough, on a straight level highway, I think I might only average about 37.
 
pearljam724 said:
I’ve owned several A and B body Chryslers. All with small blocks. I just bought a superb condition, 2 owner 72 Scamp with a slant 6 with 60k original miles. I just returned from a 200 mile trip with that Scamp and averaged 28 miles per gallon !!!
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If I add the mileage my truck gets, to the mileage my wife's car gets I don't think I'd hit 28

Of course, neither one of those are slanties.
 
cudavert said:
Not sure if everyone tuned into his statement that he did a fair amount of "drifting" going down long mountain passes. Not saying it's cheating at all, but it does skew things a bit from how MPG might normally be tested. I personally test my average fuel mileage everyday on my 2010 commuter corolla, 155 miles/day total (hey, it's a boring drive). On the long downhill pass in the morning, I can coast over 7 miles and so my record is, I have averaged just a hair over 60 MPG on my morning commute! In the afternoon going home and UP that pass.....I will average right about 32 ~ 33. Oddly enough, on a straight level highway, I think I might only average about 37.
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I also stated I returned the same exact route. Therefore, I climbed the same exact hills I descended. I did not say Long mountain passes. It is rolling hills if you’re familiar with 79 south West Virginia. Regardless, I guarantee I could best 27.8 miles per gallon by at least 2 miles a gallon if I did the calculation on a flatter route.
 
I believe it! Low mileage slant without a/c and p/s. Close enough for government calculation! Standard Deviation + or minus 2%
 
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