MPG poll

[Longhorn Man]

i always kinda wondered about the MPG on those...may as well have a big block V 8 huh?

[Brad]

My best mileage was when I had 3.08 rearend, a tonneau cover, a 2bbl Weber carb, HEI, and of course my I-6, and kept my foot out of it. I could baaaaarely reach 18mpg if I really tried. That was a few years ago and swapped the 3.08 back for the 3.73. After the truck is driving again and finances are better, I'll be putting in a 5 or 6 speed transmission.

Update: I thought I'd mention that my '67 C-10 gets about 17mpg @ 65mph with the T-5 in it. Although the speedo gear in the trans isn't correct for the 3.73's out back, I've checked mileage from gas station to gas station using a GPS unit and a 50 mile flat stretch of highway. It would be even better at 55mph.

[Robert1970C20rstbukt]

Originally Posted by Striker169

I know where Seguin is my dad grew up there what did you do down there?

a tree had fell over at my Grandparent's old house and my Dad and I went up there to cut it up. we had to take my truck because my Mom didn't want us hauling an old oily chainsaw and a couple gallons of mix gas in the back of her 02 Trailblazer.

[69TowRig]

In the entire year I've owned my truck I have yet to burn a tank of gas, so I have no idea...

[Longhorn Man]

LOL! My longhorn took 3 years to burn a tank of gas, then another 6 months to burn the second tank!

[kbs71]

I picked 15 to 17, I regularly get @ 15.5 to 16 MPG out of a unknown rebuilt 350 short block, stock heads with a valve job, edelbrock manifold and a holly 670 avenger, with HEI. I got the truck from my Mom after my step-father passed away 2 years ago. He had put the engine in it in 1998 and never got it started. All the info I have is from old receipts and notes he left. I trailered it 1000 miles home, adjusted the valves got a new qjet and it started right up. talk about lucky she GAVE me the truck, it cost me a couple hundred in gas to get it home.

[shelby987]

70 k20 with full time locked front hubs, 250 I6 with single bbl rochester, 3spd saginaw, 285/75/16 tires, and 4.56 gears! I have been told highway rpm is around 3,700....looking to upgrade to 4.10's, hei, 2bbl with large vac. secondary and smaller primary, manual hubs, 4 spd saginaw for better gear spacing, and possibly an aux overdrive.....but right now the mpg sits at 11.5 city and that includes a regular 10-15min warm up time every morning before my commute to work.
14 ish on the highway if i keep it below 70mph but considering the setup, I think there is definate possibility to push the 20mpg barrier.
bought it and drove 220miles home on a fillup, and still had a couple of gallons left in the tank (could hear them sloshing around as I took corners).

[GMan69]

MPG is around 13. Mildly modified 355 with THM400 and 3.73 gears.

[davidh]

I have a 68 with a unknown 70;s 350. It was 2bbl and points, turbo 350, 3.73 gears and I got something like 8mpg in city, Changed the the cam to 262compXtre and perfomer intake, quadrajet and it got 11mpg. Now the head gaskest is blown or the crappy 624castings are cracked. need to tear it down. I got a 81 4x4, 33's, mild 400 and that truck is thirsty in town

[VinceY]

71 LWB with a 327 gets 15 highway.
72 blazer with a 350 gets 13 highway.

[72MARIO]

Wow I thought I was doing bad..... My 84 get'sunder 12 all the time that with grandpa driving it. 355 RPM intake hedders 1406<POS...700R and 3:45's

67 gets 12 MPG thats a 355 all the info in sig. and the foot can go into it once in a while.

[davidh]

I forgot I put together a 83 1/2ton a few years ago, 350rebuilt, small valves(smaller than 1.94,) mild melling cam, fresh quadrajet, duals, 3.08 gears. I got 15mpg on the highway pulling a unloaded car trailer. I listened for the trucks sweet spot and kept it there. I did the mileage by milemarkers not incorrect speedo's. I was suprised. In town was about 12-14.

[71chevytruckguy]

when my 69 was running, it got 10 mpg. with 250 straight 6 with hei, 3 spd saginaw, 3.43 gears, 275/60/15 tires. its gettin a build 350 soon so i can get her back on the road

can't say for my 71. it ain't used a tank in the last 2 years. hopefully we'll find out within the next 6 months.

[dyingdeadman]

i get right about 10. big block, nuff said.

[_Dick_]

My 67 was built to be a daily driver ,mpg vary from 19.5 lowest to 22 with ac .its a 4.3 i keep it tuned and it runs great

[GM72K10]

My 72 K10 gets about 12 mpg. Lockouts, 3:08 rears, dual exhaust, 350 4V, TH350, A/C, LT235R75/15 tires. 72 K2500 gets about the same. Original 350 ,4 speed, Lockouts,4V,4:10 rears,dual exhaust. My 04 K3500 only gets 9.5 mpg if I'm lucky!

[Rusty Old Chevy]

i couldnt honestly tell ya what mine gets for gas mileage....i drove it home from the salvage yard and it has sat ever sence....lol....but by the end of april the motor should get bout 7-9 mpg if iam lucky muhahahaha, soon as i pull the motor and trans ill take a bunch of pics of the motor build up for everyone

[1969K10]

just voted (13-14), that is corrected for my oversize tires... i'm getting 8-9 without the correction. anyway, mild 350, SM465, T-221, 3.73 gears & 33X10.5's

[kpkoncepts]

87 fuel injected 350 crate motor, intake, air raid, carb, 700r4 tranny, 4:10 gears, 4x4, on 35" mud grapplers 3/4 ton axles. when you get off the gas, the truck coasts like a brick. im getting around 10 mpg. when you think of it alot of new SUVs dont get much better.

[Already Gone]

I'm in the 10-12MPG range. I bought the truck the way it is with a 396-350 hp engine with an Edelbrock carb ( I do not know the CFM of it ) and TH400 trans with shift kit and 3:73's out back. At 70 mph with my 235/70R15 ( 28.2 inch tall) Eagle RSA tires I'm at 3000RPMS.. I know a 700R4 would get my r's down to about 2100 at that speed and would get my mileage up to maybe 14/15 MPG but I'm scared the 396 will chew it up and I only drive the truck 2 to 3000 miles per year.

[Aarons72s]

Well my green and white gets say 10 to 12mpg. Sometimes more sometimes less. It all depends on her mood of the sbc 350, how much fluid is in the transmission( equiped with sieve th350, converter seal shot, eats 2 to 4 quarts a week you always can tell where I park by the lake under it. would replace seal but transmiision slips, chunk missing out of bell housing, and so on) and 3.73 posi. Some days she rolls real nice other days she rolls like I am towing a boat. She is just tempermental. As for my ornage and white well she has been dead since 2001. 350-350 3.08 gears. Sucked gas but probably because most of the lobes on the cam where gone and loose timing chain. Aaron

[jimmydean]

Last time I checked (I try not too very often) I was getting close to 15 on average. Low mile motor, Edelbrock intake and carb, HEI with good wires, plus I try to keep my foot out of it whn I can.

Now that we have E85 near by, I will be converting my fuel pump and lines. $.20 cheaper a gallon baby!

[mrein3]

The mpg thread lives!

Originally Posted by kpkoncepts

87 fuel injected 350 crate motor, intake, air raid, carb, 700r4 tranny, 4:10 gears, 4x4, on 35" mud grapplers 3/4 ton axles. when you get off the gas, the truck coasts like a brick. im getting around 10 mpg. when you think of it alot of new SUVs dont get much better.

Not exactly.
My '04 Explorer (V8, 373 limited slip rear) got 20 this past weekend with the kid, wife, dog, and gear loaded. In the fall of 04 I was getting 21 - 23 mpg on a road trip out to Wyoming for an elk hunt.

Originally Posted by jimmydean

Now that we have E85 near by, I will be converting my fuel pump and lines. $.20 cheaper a gallon baby!

Take careful measurements of your mileage. Most folks with factory equipped flex fuel (can run both E85 and regular unleaded) see a 20% DECREASE in mileage with the corn crap. Plus you'll have to adjust your timing to where you'll have to change it back to run regular gas. Which may be a bit of a pain on a road trip where you may not find E85. What co-workers here are seeing is the SAME miles per DOLLAR with E85 verses regular unleaded.

[67Cowboy]

Well with the old 454 you could actually watch the gas gauge move when you kicked the 4bbl in, But the 396 I built with the fancy heads a old style Performer intake and Holley Economaster 650 Spreadbore got 15mpg and a little better if I kept my foot out of it, of coarse I had the heavy spring in the vaccum secondary so it made that easier to do, but right now my 283 with Edelbrock 1407 I get about 10-12 and hope to change to a TBI set up and Aqua-tune water jet to help that out a bunch.

[clay68c10]

8-9mpg. 454, HEI, th400, 3.07 rear, edelbrock 750.
When I put the TBI on it I hope to get over 10