is 10 mpg normal?

[tekno62]

my trucks is a stock 350 with a turbo 350 behind it. is 10 mpg normal? I was told and it looks like it that the motor is a chevy crate.

[Sinister]

Yes.

[jrdv]

That is about average for all of mine. It does have the wind resistance of a brick!

[tekno62]

LOL god I need a 700r in it

[oldblue1968chevy]

wat would u get with 700r4

[tekno62]

the overdrive. may get 12 mpg then

Originally Posted by oldblue1968chevy

wat would u get with 700r4

[texanidiot25]

Yeh, if you do any freeway driving, the 700R4 will do you good. But 10 mpg is about normal.

[67_C-30]

I don't know what your truck is (C-10 or C-20?) and I don't know your gear ratio, but all of the trucks I've had with 350's/TH350's and 3.08's got better than that. I get around 14 - 15 in my red '69 SWB 350/TH350 and just slightly less (oddly enough) in my blue '69 SWB 250/3OTT. I've has others that get 12 - 13, but I never had one that gets 10 unless it was 3.73 geared 1/2 ton or a 3/4 ton or bigger. I don't putt around like grandpa, but I don't drive like I did when I was younger either.

[FRENCHBLUE72]

My blazer gets about 10 and its like pushin a brick through water..

[Longhorn Man]

10 - 12 is average. http://67-72chevytrucks.com/vboard/s...d.php?t=172346

[dwcsr]

I was getting 10 down hill. I put a Holley spread bore on it and jetted it back to 58's added an 1-5/8 phenolic spacer. R45ts plugs at .050 with one of those white's speed shop HEI's. I get 13 now. I have a 700r4 to put in and hoping for 16-17.

[kookykrispy]

10 mpg is normal... just for comparison, my '99 silverado is not much better. its a 2500 4x4 extended long bed with the 6.0 and I get 12-13 on the highway

[Gray Ghost]

I'll chime in with that being normal as well. I can't imagine getting more than 12 unless you drive like grandpa and never break 30mph. My best numbers with a new motor and good tuning is 11.

[nightmare]

I normally get 11.75 to 12. that's with a stock 350/th400 and 3.08's posi. now if i run the a/c, i get around 10, but i'd rather go with the windows down. i'm changing to a 355 and 700r4 this weekend, so if i've done my calculations correctly, i'll be sitting at 16 or 17 mpg after the swap.

[monte0185]

I had a 4wd 79 blazer that my dad gave me that had a sb400 in it that was completely stock. I got 9mpg no matter if you were pulling a 16ft trailer with a 1972 chevy truck or just driving it down the road. After awhile the quadrajet started to leak and rather than buy a kit to rebuilt it i had a carter afb I threw on there cause it was laying around and it jumped up to about 15.5-16mpg. I loved that blazer. Had to much cancer to try and save though. Good ol nebraska truck.

[samwise68]

Maybe it's my little engine, or the gears or...something, but 10, in my opinion, is fairly low.

My truck, even as tired as it is, gets a solid 15, with jaunts up to 17-19 if the weather and gas is good, and I only drive highway with minimal hot rodding.

More info would help, but, like the other guys said, it's normal...just, not with my limited experience.

-Sam.

[Senator350]

Originally Posted by kookykrispy

10 mpg is normal... just for comparison, my '99 silverado is not much better. its a 2500 4x4 extended long bed with the 6.0 and I get 12-13 on the highway

X2

I got up to 13 with a Edel carb #1404 on a 327/th350
The 1404 is sized for a 305 and rated for milage, not performance.
It's an easy swap for a long trip.

Newer big trucks aren't doing much better. My old boss' '02 2500 quad cab longbed SRW gets around 12 on the highway.

[americanmusc1e]

I have a Holley 600 vacuum secondary with the black secondary spring(keeps the secondarys closed 90 percent of the time) and the best i got was 12.5 Highway, but i stopped checking my mileage when gas prices went down

P.S. i got 9.8 with the A/C on

[El Jay]

I have a 350 in my Chevy and a 402 in my GMC; both with 4.11 gears.
Both of them get around 10 MPG combination city/freeway driving, & about 13 MPG cruising the freeway & staying out of the secondaries.

Having the aerodynamics of a barn doesn't help a whole lot, to be sure.

[tekno62]

there an easy way to find the gear ratio for my rearend?

[Woody]

The quickest way to check your gear ratio is to jack up both rear tires, then turn the drive shaft and count the turns it takes to rotate the tires one full turn. make sure both tires are turning. So then 3 - 3/4 turns of hte drive shaft for 1 rotations of the the tires is a 3.73 gear. a little over 4 is probably a 4.11, a little over 3 is probably 3.08.

You also can look at the glove box sticker, it may have it listed if it is still there and the rearend hasn't been swapped out.

Oh! I have a 350 / 400t w/ 3.73 gear and it only got 12mpg. I installed a 305 (from a 86 chevy) with HEI and the best I could ever get was 13-13.5 on the highway running 65-70. Like everyone else it really does not matter if it was loaded or not....

[tekno62]

the spid just says positraction rr axle

[Longhorn Man]

Originally Posted by tekno62

the spid just says positraction rr axle

Assuming the info you provided is as it was built originally, (350/TH350) and nothing has been chainged, then it'll be a 3.07 gear out back. That was standard with that eng/trans combo.

[67ChevyRedneck]

I have a 350/700R/3.73 and I'm getting a consistent 12.5-ish mpg with all of the "city driving" I do. It see's OD only about 25% of the time. On the highway I can squeeze out 14.5-16mpg, completely dependent on speed. I try to have a light foot, but there may be a few spirited romps per tank

For comparison, my silverado with the 5.3/4l60E/3.73 gets 14/18 under the same conditions.

Here's the average economy I got over quite a few tanks when I first installed the 700R. The 14.36 was a mix of lots of highway and some city, I rarely do highway trips, so I don't have those written down, but I do check them.

12.65
12.46
12.79
12.79
14.36
11.93
12.46
13.01
12.53
11.96

[tekno62]

No idea really - I'll jack up the truck toniht and do the wheel spin.


I got this truck to do some camping in so any pointer on upping the mileage would be great.

Originally Posted by Longhorn Man

Assuming the info you provided is as it was built originally, (350/TH350) and nothing has been chainged, then it'll be a 3.07 gear out back. That was standard with that eng/trans combo.