gas milage

[caspear78]

found out today around about what im gettin in gas milage, rite now im lookin at about 12 mpg with the tail gate off, filled up yesterday and then ran around till about empty and added it all up when i filled up again today,so rite now 12 aint to bad but i want to get alittle better then that,im thinkin about gettin a 700r4 and havein it rebuilt and havein another rearend put in under my truck,,, what are yall runnin and what are yall gettin for gas miliage

[SWEET7T]

1/2 ton, LWB, 2wd, 327ci with 2-barrel carb and points ignition, 350 tranny, and 3.08 rearend. running 255-70R15 tires. I get 13-14 doing 75 down the road, and about 14-15 in town. If I cruise doing 50-60 I can get close to 20mpg.
And that's with my tailgate closed

[Stocker]

Most of my miles are in town, short trips, and include warm-up (choke on) time. I haven't checked my fuel mileage in many years (I don't actually get mileage, I get yardage!). But when I took a 3500 mile trip a long time ago, I averaged 11 mpg with a camper shell on my lwb K20, 4:10 gears. Oh yeah, that was winter & included a few hundred miles of locked-in 4wd (Rockies etc).

[Superman]

haha, i hear that, i hardly drive far off, with the v8 and all.

[caspear78]

im runnin a stock 350, edelbrock 650, headears, hei, turbo 350, not sure on the rear end but im runnin 255-60-15 out back,, i took a 142 mile trip and filled back up this mornin and thats how i figred out what im gettin, i put just over 12 gallons in and went from there

[72 CustomCamper]

The last time I drove my truck it got around 3 mpg. 72 C/20 400 hp 402bb,700R4 trans without TV cable, 4:11 dana 60 rear...

Chuck

[LUV2XCLR8]

NOT AS BAD AS 72CUSTOM, BUT 8 MPG HERE - 400 SB W/ 4 BOLT
MAINS, 2 SPD. POWERGLIDE, EDELBROCK 750, VICTOR JR INTAKE,
ACCELL WIRES, HEADERS, FLOWS, VELOCITY STACK, AND UNTIL
LAST WEEK 3:73 REAR END WELDED, IT WENT CRASH @ 120 MPH

[Longhorn Man]

Try it again with your tailgate on and up, you may find that it has little to no effect on your MPG.
Also, if you do the 700R4, and if you have the 3.07 gear, your MPG will more likely than not drop. Some can get it to work with that combo, but my money will be on loss of mileage.

[Steven Sellers]

Andy, Its kinda funny you mentioned that fact as I was just telling a buddy about there being no difference today.
I watched a show on TNN a few years ago and they took a compact, mid size, and a fullsize truck and put tailgate down, took it off , ran one of those net things, and then put a tonneau cover on it.
The wind tunnel is what they used and the results showed there was no difference with the tailgate down or anything else as the wind still came in the bed and made a swirl whether tailgate was there or not.
The one thing that did work though was a toneau cover as the wind could not get in. I wish I had of taped it because everytime I tell anyone about the results they just laugh and swear theirs gets better with tailgate down or off.
Steve

[Longhorn Man]

I learned the hard way...no fuel guage, and i was shocked that my MPG was so pathetic being I had the same engein and tranny in a smaller and lighter truck with more freeway friendly gears. (took the eng/tranny out of the totalled longhorn and installed it in the SWB GMC) My MPG went from 14 combined, down to 9 combined. I dropped the tailgate expecting at least one MPG better, but I ran out of gas at the exact same point.
I fixed my fuel guage becouse it was easier than keeping track of my MPG every week.

[Jeepster376]

After first round tuning I'm getting just about 13 mpg, but I found my float levels were way high, and I'm still changing over to synthetic fluids. So I hope to have better numbers as soon as my new axle shows up hopefully tomorrow. I also still need to find my ideal timing, and tire pressure, and may try a tonneau cover. Maybe I'm crazy, but I would like to get 18 out of this thing. 72 K10 350/TH350, 3.07, 35x12.5" tires, Carter AFB, mallory unilite ignition, and dual exhaust.

[dwaite72lnghrn]

Right now I get between 9.5 and 11.5mpg. 402bb/1411 edelbrock/th400/4.11 gears/9.50x16.5 bias tires. with the old Q-jet I averaged about 12mpg and a high of 14mpg. When I ran the q-jet I would get about 1/2 mpg better with the gate down than with it up and it actually dropped when the gate was off. This was not scientific just everyday driving back and forth to philly 125miles 1 way turnpike. I think I might try the q-jet again to see if it can still get 12 average.

[shortymac83]

I can personally vouch for the effectiveness of a quadrajet. I went from a 2 bbl carter carb on our jeeps 258 to a 650 cfm holley and got about 16 mpg on the highway (as opposed to 18 mpg with the 2bbl). Threw on a 750 cfm quadrajet off of a Olds 350 and it got 21 mpg on the highway. Granted, these tests weren't done with any kind of control, it was just what I observed on different days with similar conditions (similar temps, no wind, etc). I'm sold on quadrajets, my 307 with a CCC 800 cfm qjet gets 25 mpg on the highway and 16 in town. Can't beat those dinky primaries and cavernous secondaries.

[ckhd]

1972 K10 Suburban - 350, stock exhaust, weiand intake, q-jet, 700r4, 3.73 - 10-11mpg

1968 K20 - 350, sotck manifolds, q-jet, stick, 4.57 - 7mpg

1969 K10 - 350, stock intake, cheap-o headman headers, q-jet, stick, 3.73 - 19mpg

1999 K10 Suburban - 350, stock everything, port injection, 4l60e, 3.54 - 14mpg