What sort of fuel mileage should I expect?

[Kwik_Cutty88]

I'm just trying to figure this out with the upcoming school year. I have a 50 mile round trip commute to school 4-5 days a week. All the specs to my car are in my sig. Right now it has a 2.56 non posi. I know it's hard to tell without actually doing the calcuations, but I figured I could get close with a rough estimate. I'm thinking somewhere around 15 mpg. Also I think the tank is 17 gal, is this right?

 

[marcar1993]

Idk about your mileage but a g body tank is 18.9 gallons.

 

[jrm81bu]

The replacements I sell are listed at 17 gallon. 18 gallon for a wagon.

 

[azmalibuwagon]

15 mpg is as good a guess as any at this point. You'll want to fill up while you still have a couple gallons in the tank, so if you fill up Monday morning, you'll need gas by Friday.

 

[pencero]

Hey you are only running a 500 cfm carb! If you don't have gasket issues/ exhaust leaks/ smoke on startup and all that I don't see any reason why you cant get your car closer to 20 mpg w/ that stock rear end. If you don't know how to tune it yourself take it to somebody who does and tell them what you want, but if mileage is your goal than don't use the a/c, put your windows down on a long trip and set your air to 'heat' put it up 1 or 2 notches to help cool. If your shocks are in good shape then travelling w the windows open should push down but not 'sink' the car down in back over 65 (which destroys your mileage because then the car is wallowing in a 'drunk' suspension if your maintenance is behind back there)

I haven't seen your car in action but I can tell you for a fact that I recorded 21 mpg with a 350 truck engine bored about .20 over using a holley 650 after I got a fresh tune up in my 79MC ! and that was with the 3speed! Don't limit your possibilities, set a reasonable goal and then attain it! Remember, if you're getting better mileage but the car isn't running sluggish you are extending the longevity of your engine anyway - you have nothing to lose and everything to gain! That 79MC I had was with a faulty fuel float, so we had to track the ammount of gas in the car/ mileage with cell phone apps to avoid running out of gas. If I would have kept the really crappy 'rochester 380' carb that had came on that car it would have done maybe even more than 20 mpg

 

[dogsht]

Your title says mileage but your content suggest distance to empty. Are you trying to estimate how far you can go on a tank?

fwiw
An old cheapie gas miser car bought cheap ie less than a grand and used for the commute might pay for itself.
A working lock up torque converter is good for 1 to 1.5 mpg.

 

[Kwik_Cutty88]

Hey you are only running a 500 cfm carb! If you don't have gasket issues/ exhaust leaks/ smoke on startup and all that I don't see any reason why you cant get your car closer to 20 mpg w/ that stock rear end. If you don't know how to tune it yourself take it to somebody who does and tell them what you want, but if mileage is your goal than don't use the a/c, put your windows down on a long trip and set your air to 'heat' put it up 1 or 2 notches to help cool. If your shocks are in good shape then travelling w the windows open should push down but not 'sink' the car down in back over 65 (which destroys your mileage because then the car is wallowing in a 'drunk' suspension if your maintenance is behind back there)

I haven't seen your car in action but I can tell you for a fact that I recorded 21 mpg with a 350 truck engine bored about .20 over using a holley 650 after I got a fresh tune up in my 79MC ! and that was with the 3speed! Don't limit your possibilities, set a reasonable goal and then attain it! Remember, if you're getting better mileage but the car isn't running sluggish you are extending the longevity of your engine anyway - you have nothing to lose and everything to gain! That 79MC I had was with a faulty fuel float, so we had to track the ammount of gas in the car/ mileage with cell phone apps to avoid running out of gas. If I would have kept the really crappy 'rochester 380' carb that had came on that car it would have done maybe even more than 20 mpg

Wow! Good post man, thanks for the tips and encouragement! It runs like a dream, so it's gotta mean its tuned pretty good haha. Just one question though, would traveling with the windows up be better for fuel economy?

 

[Kwik_Cutty88]

Your title says mileage but your content suggest distance to empty. Are you trying to estimate how far you can go on a tank?

fwiw
An old cheapie gas miser car bought cheap ie less than a grand and used for the commute might pay for itself.
A working lock up torque converter is good for 1 to 1.5 mpg.

Sorry about the confusion, I am looking to get a rough estimate on what MPG i will be getting. My torque converter isn't wired up yet, but by the time I go back to school it will be. I didn't know some simply wiring would be good for almost 1.5 more mpg! 8)

 

[redster]

I'm not good with math (at all) but i don't drive the piss out of the car, and i get around 500 or more kilometers per full tank ( this is with a 267 v8 w/ 3 speed). I just hit half a tank and my trip counter says 320 kilometers.

 

[Lorenzo]

Well i dont know if this is just my car but i think i get pretty shitty mileage. I have a new Rebuilt Carb on it, engine is fully tuned up, wheel alignment done and more. The farthest ive gone so far is 378 km and i was almost at empty. I fill up for about 63$ which is about 49 liters of gas. I dont punch it, i rarley open up the secondaries. Engine is a 305 5.0, not the H/O. I wish i got the mileage you got with that 267!