Best MPG for a 2wd 67-72

[72 cheyenne pdx]

I get around 12-14 with mix. Straight hwy, I am around 15-16. I am carryin g a 500lb custom canopy/camper. Stock 350 motor, except the carb (Edlebrock 600cfm), and new 3" single exhaust. I know, at the time I could afford dual exhaust, and I was tired of the exhaust coming into my cab whenever I had the windows down. 3.73 gear, th350. I believe I might get better if I didn't have the camper on it. Well see in the future.

[JameslovesJammie]

1965 GMC 2wd longbox stepside
283 2 barrel, granny gear 4 speed (SM420 I think) 3.07's, points
Pulling a 4x8 trailer with a yard tractor all day, around 14 mpg.

My trick was to shift at the lowest rpm's I could and do ABSOLUTELY NO jackrabbit starts or powershifts.

[Myself]

I thought my wife's truck was kind of a hog, looks like we're doing pretty good! 1968 swb .040 over 350 with speed pro hypereutectic flat tops. Comp Extreme Energy 268h cam. Worked over 1406 (305 H.O.) heads for a 9.8:1 comp. ratio. Edelbrock Performer RPM intake, Holley 600cfm va. sec. 4 bbl. Stock HEI dist. Hedman long tube headers to 3" pipe breathing through Full Bore mufflers. TH350 trans with B&M 2200 stall, 3:73 rear gear and 295/50-15 tires. Getting about 14 mpg average mixed driving. Got 8mpg two weeks ago pulling a 2500# trailer with 4200#s of scrap iron over about 50 miles!!

[Brad]

After finally getting all the bugs worked out of my drivetrain for the most part, using the 250/T-5 combo I'm getting about 17mpg @ 65mph. My engine has about 140,000 miles on it and I think it might be .30 over, but can't remember. These L6's aren't known for their high compression and I suspect with a good solid rebuild and 9.5:1 comp ratio, I could get kick @$$ mileage from this. Most likely in the spring I'll experiment with a Q-Jet and try to get better mileage since they have smaller primaries.

Since I know I'm getting 17 @ 65mph, I should be getting higher mpg's at 55mph. That's on a tired, old engine! My eventual goal is 21-22 mph highway!

I used a GPS since my speedo is just slightly off. I notice that when it says 75- I'm actually doing 70. 55 is about 54, etc. That's why I don't really trust many of the numbers thrown around this board regarding mileage- even what people tell me in person until I can really question how they came to their conclusion.

Here's my combo: Rebuilt 250 w/possible .30 over pistons, stock cam as far as I know, 500 cfm 1403 w/stock jetting and rods, HEI which probably needs a rebuild, Clifford intake and shorty headers, dual exhaust with H pipe, Camaro T-5, 3.73's in the rear, tonneau cover on bed, 275x15x10" tires in back 245x15x8" tires up front. If I were to put thinner tires on it that would help mileage due to less rolling resistance.

[EAST SIDE LOW LIFE]

At over $5.00 a gal I don't sweat it. I know you want facts and figures but I'm still going to drive my trucks and car's and I'm not selling anything so I figure why depress myself. I just enjoy that moment that I'm cruz'n.

esll.

[1970 CST Short Wide]

Big Block, Lots of fun - Gas mileage? Who Cares

[Ackattack]

18.5 mpg, TPI 350, adjustable fuel pressure regulator (which I could turn down for a little bump in mileage), K&N cold air setup, 700R4, 3.73 gears, 275/50/17 tires, headers, 2.5" exhaust.

Oh, I run 92 octane too.

[NONHOG]

[QUOTE=Brad;2414923]

I used a GPS since my speedo is just slightly off. I notice that when it says 75- I'm actually doing 70. 55 is about 54, etc. That's why I don't really trust many of the numbers thrown around this board regarding mileage- even what people tell me in person until I can really question how they came to their conclusion.

I know what you mean , I question myself as to how accurate is my gauge ?
how accurate is my speedo ? I suppose it wont matter if everything is consistant you could still check for improvements or loss .
Another thing I wonder (maybe I think too much) is "click off" from station to station , is it the same ?
Bottom line is I want to drive my old beater truck (and I will ), but having decent MPG would sure help
back to the question , 9-11 MPG soon to improve with any luck !

[67_C-30]

'69 C/10 SWB

Engine:
Rebuilt 350 (.030 over so its really a 355) with flat top pistons and 882 heads making the CR 9 : 1, stock CS-274 cam, Q-jet on stock non EGR manifold, HEI, clutch fan, ram horn manifolds 2 1/4" dual exhaust.

Trans and Rearend:
TH350, slight towing style shift kit, stock converter, 3.08's

Tires:
P235/70/15's on 8" steel 6 lug rallys

I get 13-15 in town, 16-17 highway. I do mainly mixed driving and I usually get about 15 consistantly.

I am going to be adding TPI and 275/60/15 tires in the near future, and I'll come back and post results of the new combo.

[gkolmatycki]

1969 C/10 LWB

Engine:
SBC 283, stock internals, Q-jet on stock cast-iron 4BBL manifold, HEI, dynomax full-length headers into 2 1/4" dual exhaust with magnaflow mufflers

Trans and Rearend:
TH350, stock converter, 4.56's

Tires:
P235/75/R15's

I normally get about 12-14 MPG combined.

Gas Mileage.......LMAO!!!! Thats one thing I don't really care about with my truck. Its a cruiser, not a daily driver. I have my 2001 Cavalier Z24 with a 4 banger for gas mileage and daily driving.

[wibilly]

i get about 15 mixed driving in my 69 lwb c10 with a junkyard 350 from a 80 chev pu sm 465 with 3.73 gears. i have 31" tires. it's timed by ear till just shy of pre-detination needs an air filter and i never looked at a plug. i'm very easy on the throtle, never opening the secondarys, building speed before hills and backing off as vacume decreases.i travel at 65-70 mph alot so a set of 3.07s are in the plans. it needs valve guide seals so i'm gonna mill the heads to up the compression, do a good 3 angle valve job and set up a new hei. with that and a good carb tuning i'm thinking 18 - 20 plus is not out of reach with a light right foot

[mnunn454]

Originally Posted by TP from Cntl PA

Got 15 or so with the 350 in my '71 C-20.............Put the Cummins in it, and it doubled and then some! No highway use, just two lane black top and gravel roads/lanes.

Wow! Are you serious?

30+ non-highway MPG in a C-10 by swapping to a Cummins Diesel?

Tell me more...........

[69halfton]

about 13 mpg on the highway @ 65, when im trying to save fuel..

suckin gas..
and haulin ass!

[EAST SIDE LOW LIFE]

Originally Posted by 1970 CST Short Wide

Big Block, Lots of fun - Gas mileage? Who Cares

**********************************************************

Right on!!!!! It's worth the price for the rush.

edll.

[BCOWANWHEELS]

17.5 to 18.2 if i drive it right. 383 w 400 rods, towing cam, dart II BIG VALVE HEADS, 10-1 compression srp pistond, q-jet on iron maniflod, roller rockers, hei dist. th350 w/3.08 gears. i couldnt believe it. i triple checked it on my 250 mile trip to woodbridges picnic this summer. my 250 I 6 with 3 on tree and 3.73,s only gets 13-14 empty running 60 mph. 11-12 loaded
bob

[Dova]

anybody running a 327? I bought a 71 with a 327 with a 350 tranny and wondering what i would get mpg. it has 3.08 gears. and how much would a 700R4 improve the gas mileage?

[jkaylor68gmc]

Mine improved it about 5-7mpg. I purchased a lock-up style 700R4.

[Ackattack]

Originally Posted by Dova

anybody running a 327? I bought a 71 with a 327 with a 350 tranny and wondering what i would get mpg. it has 3.08 gears. and how much would a 700R4 improve the gas mileage?

I did have a 327 TH350 with 3.08 gears. It had a Comp 268H cam and edelbrock carb on it. It would get ~12 mpg.