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Old 07-21-2009, 07:38 PM   #26
MoFaster
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Re: What's your fuel Mileage?

Around 3 or 4 with a 402, tunnel ram, and 2 600 hollys not sure with tha predators.
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Old 07-21-2009, 07:49 PM   #27
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Re: What's your fuel Mileage?

Around 3 or 4 with a 402, tunnel ram, and 2 600 hollys not sure with tha predators.
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Old 07-21-2009, 07:57 PM   #28
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Re: What's your fuel Mileage?

Quote:
Originally Posted by swb85 View Post
383ci, 750cfm edel carb, m21 4 speed, 3.42 gears and 28" tall tires. I usually average around 15-16mpg mixed hwy/city. Usually around 17 on the highway. I bet I could break 20 with an overdrive!
how many rpm's are you turning on the highway?
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Old 07-21-2009, 08:32 PM   #29
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What's your fuel Mileage?

1979 C-10 long box... modified 355 pushing 425 hp, with a 4 speed currently. When "grannying" it & cruising, have achieved a personal best of 18.7 mpg.

When hammering it, going through a set of rear tires in an evening, and filling out environmental impact statements, have achieved a personal best of 4.8 mpg.
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Old 07-21-2009, 09:01 PM   #30
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Re: What's your fuel Mileage?

Quote:
Originally Posted by 78 Big10 454 View Post
Stock 454 with a TH400:

10 mph on a good day.
10 mph on a bad day
10 mph highway.
10 mph city.
10 mph empty.
10 mph loaded.

Did I miss anything?
10 with a tailwind?

I can get 18 or so if I drive like a citizen. With the 3.07 gear and the OD the engine only runs 1600 at 62 mph (100km/h), so I usually run about 1800-1900 at that's 70-73 mph. That's with the converter locked up and no winds. Sounds silly, but a little wind here is 25 mph +.
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Old 07-21-2009, 09:13 PM   #31
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Re: What's your fuel Mileage?

Iget around 9mpg,less when my foot get's heavy
90 jimmy,mild 350,tbi,33" tires and 4.10 gears
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Old 07-21-2009, 09:15 PM   #32
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Re: What's your fuel Mileage?

My 1989 TBI 1/2 ton Suburban 2wd,I get 15-16 going back and forth to work,taking it easy.My crewcab Dually,with 30 over 454,with towing cam,turbo 400w/ 4:10,Im getting about 9.5 empty,7.3 towing.My 2wd 4 banger Sonoma 5sp gets 28-30 driving to work and back
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Old 07-22-2009, 12:07 AM   #33
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Re: What's your fuel Mileage?

8-10mph mixed city/hwy. 350 4bbl and th350 w/ 3.42 (29" tires)
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Old 07-22-2009, 12:18 AM   #34
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Re: What's your fuel Mileage?

my 87 3/4 ton 4x4 tbi w/ a tired 350/th400/4.10 gears is 8 mpg and that is driving nice.

my 89 1 ton crewcab dually 4x4 tbi w/ freshly built 454 rv cam / th400/4.10 gears is 8 avg and 10 if i baby it.
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Old 07-22-2009, 12:30 AM   #35
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Re: What's your fuel Mileage?

umm more like 12-13 mostly city
even with a 305 but a th350 and a 3.42 gear
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Old 07-22-2009, 12:31 AM   #36
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Re: What's your fuel Mileage?

Quote:
Originally Posted by 78 Big10 454 View Post
Stock 454 with a TH400:

10 mph on a good day.
10 mph on a bad day
10 mph highway.
10 mph city.
10 mph empty.
10 mph loaded.

Did I miss anything?
Man you drive slow only 10 mph
sorry had to do it

Mine is a 454/rv cam/10 to 1 heads/600 eddy/th400/4:10 gears and like you it's only 6 mpg all the time no mater what I am using the old girl for.
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Old 07-22-2009, 01:19 AM   #37
78 Big10 454
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Re: What's your fuel Mileage?

Originally Posted by 78 Big10 454
Stock 454 with a TH400:

10 mph on a good day.
10 mph on a bad day
10 mph highway.
10 mph city.
10 mph empty.
10 mph loaded.

Did I miss anything?

Yes - 10 mpg with the engine shut off and coasting downhill.

K

Good catch, Keith!
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Old 07-22-2009, 06:01 AM   #38
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Re: What's your fuel Mileage?

87 1/2 ton w/topper, 6.2 diesel/700R4 and I believe 3.08's, 24mpg mixed (it's 37 miles 1 way to work, dirt, paved country, 4 lane expressway, and 5 miles of 6 lane city roads).
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Old 07-22-2009, 09:14 AM   #39
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Re: What's your fuel Mileage?

Quote:
Originally Posted by mongoose View Post
how many rpm's are you turning on the highway?
2700rpm @ 70mph
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Old 08-09-2009, 09:02 PM   #40
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Re: What's your fuel Mileage?

13.8 city 17.8 hwy last long trip.
85 longbed c10 with 305ci 700r4
i run lucas in the oil. every other tank i use lucas
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Old 08-09-2009, 09:22 PM   #41
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Re: What's your fuel Mileage?

What do you think my new rig will pull mpg? 87 350TBI 3/4ton, sm465 creeper box and either 3.73 or 4.10 gears..... at 60-65mph on the highway. Can I hope for 12-14?
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Old 08-09-2009, 09:48 PM   #42
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Re: What's your fuel Mileage?

1983 single cab dually, 454 hiped up a little, stock quadrajunk, sm465, 4.10 gears, manifolds, 2 1/2" duals, 3" tips, 9" glass packs, CB radio

7-8 in the hill country
13 if i go easy on it
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Old 08-09-2009, 10:23 PM   #43
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Re: What's your fuel Mileage?

Yesterday I got 13.5 @ 70mph with the air on in my '84 crewcab w/454/TH400/14blt 3.73 and 265x75x16's...
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Old 08-09-2009, 11:20 PM   #44
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Re: What's your fuel Mileage?

Quote:
Originally Posted by swb85 View Post
383ci, 750cfm edel carb, m21 4 speed, 3.42 gears and 28" tall tires. I usually average around 15-16mpg mixed hwy/city. Usually around 17 on the highway. I bet I could break 20 with an overdrive!
17 with no o/d?
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Old 08-09-2009, 11:21 PM   #45
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Re: What's your fuel Mileage?

So far I win with best mileage.
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Old 08-10-2009, 06:08 AM   #46
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Re: What's your fuel Mileage?

not so fast third street!

i get 17mpg city depending on how heavy my foot is and 20mpg highway
i have 86 scottsdale with 305/700r4 and 2:73 gears. goin nowere fast in this thing
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Old 08-10-2009, 06:42 AM   #47
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Re: What's your fuel Mileage?

83 305 HO with a screwed up 700R4 and Holley 600 4-barrel. Best is 15 MPG mostly 12-13 MPG cause my right foot.
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Old 08-10-2009, 07:09 AM   #48
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Re: What's your fuel Mileage?

Quote:
Originally Posted by thirdstreettito View Post
So far I win with best mileage.
Quote:
Originally Posted by INSIDIOUS '86 View Post
not so fast third street!

i get 17mpg city depending on how heavy my foot is and 20mpg highway
i have 86 scottsdale with 305/700r4 and 2:73 gears. goin nowere fast in this thing

Nuh-uh guys - I said 22 mph with my little V6 and manual overdrive!

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Old 08-10-2009, 07:51 AM   #49
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Re: What's your fuel Mileage?

And you better check out my diesel numbers! Get 22mpg with bad pump and heavy foot LOL! Taking it easy is 24mpg no problemo.

Next build is 82 1/2 ton 3.08's 250L6 with A-833 like Keith's. I drive like a little old lady so I bet I can get 22mpg out of it! If not than I'll swap in my 194 Nova motor and toss on TBI. That'll get ya!
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Old 08-10-2009, 08:45 AM   #50
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Re: What's your fuel Mileage?

I was getting around 15-16mpg Hwy before they imposed crap E10 gas on us, now I get 10-12mpg HWY. The truck never runs quite right now since it has no computer and seems to need to be recalibrated slightly for each tank of gas, since the gas is never the same from tank to tank.

78 c20, 350sb th400 3.73 rear end. 4950lbs.


I don't list what I used to get in my '87 since everybody always calls BS.

Last edited by 78 Chevyrado; 08-10-2009 at 06:03 PM.
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