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Lets hear some MPGs

I might add that when I first got my '72 K5, it had a 283 intake on it with the smaller Rochester 2GC carb off a '67 Impala the previous owner swapped on it,he insisted it ran "way better" with it than the Q-jet it had originally...

He had the original intake and carb and he gave it to me when I bought the truck..I drove it a good year with that 2 bbl on it,and it didn't seem to get any better mpg ,it still got around 15 mpg in combined city and highway driving..

I soon got the urge to have a 4 bbl,and I found a used Weiand dual plane intake for 10 bucks a friend had ,so I put that on it with the Q-jet..it sounded much more impressive,especially with an open element Moroso air cleaner I also got for cheap on it,but it did no better on gas,probably worse,because now I had to boot in the secondaries it sounded so cool more often...

Then I found a used Carter AFB for 25 bucks at a swap meet,I put that on it and it really ran great,much more "boot" when you kicked in the 4 barrels..it would get about 16 mpg if you drove like a granny,but when you booted it it would suck gas down pretty good,it'd get 10-12 mpg if you hot rodded it around town..

In the end,I regretted taking the 2 bbl off it,especially after I swapped a SM465 in it in place of the TH350...if you lugged it down instead of downshifting,it would buck,ping and lurch with the 4 bbl carbs...they proved to be troublesome in cold weather too,they iced up and stalled ,the chokes were not the best either,the Q-jets choke coil spring thing let it stay on too long and kill gas mileage,and the AFB's electric one was too finicky,I ended up converting it to a hand choke..

I decided to put the 2 bbl intake and carb back on it,with the stock air cleaner all hooked up right --and what a surprise--it could now be lugged down to nothing in third gear,and when you gave it some gas--it pulled up nice with no bucking,pinging or lurching..it DID have more low end with the smaller carb and intake ports--much better "driveability"....it lacked the top end thrills the 4 bbl gave though,and the gas mileage stayed about the same overall..and the choke worked right and with the "heat stove" on the air cleaner working it didn't ice up and stall on foggy mornings any more..

So in my experience a 2 bbl may not improve gas mileage much if any,but one will increase low end torque some,and give better driveability..I guess the air flows thru the smaller venturi's faster and that improves low speed performance some..
 
16.5 highway after lift
21 highway before lift :doah:
 
About 18-19 mpg mostly highway miles in my m1009. 6.2L/th400/3.08 gears/ 37" tires
 
no lift
350
700R4
10 bolts
4.10 gears
33x10.5x15 on steel rallies
Motor and transmission were rebuilt approx 2 years/5,000 miles ago.

10-12 in the city

15 on the highway if it's flat and cruising at or under 65
 
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I get about one hour per gallon on the rocks and when I used to take it to the dunes I'd burn about 15 gallons per day of fun!

Those are the only way to calculate MPG's in these trucks. :)
 
Avery4jc said:
I get about one hour per gallon on the rocks and when I used to take it to the dunes I'd burn about 15 gallons per day of fun!

Those are the only way to calculate MPG's in these trucks. :)
Click to expand...

Wow...
I get one hour per gallon idling in my big rig.:o
 
diesel4me said:
What gets me is I used to drive my 72 K5 with its original 350 (with over 100K on it) and with various 4 bbl carbs like Q-Jets and Carter AFB's ,back and forth to work 70 miles each way,and get a consistent 13-16 mpg with it...the commute was mostly high speed highway and some rural hilly roads,and I didn't putt along at 55 mph like I was supposed too then either (you'd get rear ended if you did!)..

I had a TH350 in it at first,them swapped in a SM465,with the original 3.08's in it I couldn't shift into 4th on hills and it lugged under 45 mph,so it probably increased the highway mpg some..

I think todays ethanol laced gas is the reason we cant get decent mpg,not so much the trucks or engines..alcohol has less BTU's than gasoline and thus runs leaner and you'll need to burn more to get the same power..also its oxogenated so it'll burn faster..probably flows thru the carb jets faster too...

I noticed an immediate drop in mpg back in the 90's when they started forcing us here to use oxogenated fuels and "gasohol"..when I drove to TN in my G10 van in 1992 I noticed it ran better and gas didn't seem to get guzzled as fast down there--not only was it cheaper than here,they still had "real" gasoline,not this half ethanol crap..soon as I filled up here it ran with less power and tended to lope at idle,and got worse mileage..
Click to expand...

I think this is absolutely true about the ethanol. I was on a 2,000 mile road trip in a 2006 Nissan Titan and got gas at some stations that did not have ethanol and there was a huge difference in mileage. I remember one of the stations had a sign that said their gas had no ethanol. I didn't think much of it until I drove a couple hundred more miles and started wondering why my mileage was so much better.

In my 83' short bed stepside 4x4 with 350 TBI, TH400, 3.42 gears and 31's I recently checked and got 12.7 driving back and fourth to work. Not too bad I guess.
 
imiceman44 said:
Wow...
I get one hour per gallon idling in my big rig.:o
Click to expand...

It just depends on what trail we're on and whether we're going up the mountain or down but on a typical in one way turn around and come back out that way the next day it works out to about a gallon an hour.
 
Well,I burned up almost all of the 5.1 gallons of diesel I bought tuesday (for 20 bucks) just going about 45 miles the past few days going around town to pay bills,get precsriptions filled,etc..stop and go and sitting still at red lights sucks,thats all I can say..I'm starting to wonder if my tank leaks or something,after going almost 200 miles on 15 gallons..might just be the gas gauge seems to drop quicker once it gets below 1/2 a tank,I dont know..

My "water in fuel" light came on yesterday for the first time since I owned the truck too..but it runs fine,and I have tried draining the filter and tank with the factory water removal valve and got no water before,so I doubt there is any in it..I wiggled the wires on the sending unit and it went dimmer,then out completely on my way home..I may try draining it tomorrow,I doubt any water us in the tank unless I got some crappy fuel tuesday..probably a fluje (I hope!)..

To add to the pain,I noticed the station where I used to get gas for my car,dropped the price of regular to 3.39 today..been going down since the day I took it off the road..of course..:mad:
 
diesel4me said:
I dont keep accurate records on mpg,but I put about 12 gallons of diesel in my K2500's tank a few weeks back and went over 150 miles since,and its now around 1/8th of a tank..

I would guess it gets at best 18 mph,probably less..with the thing weighing 6200 lbs empty and the engine being only 140 hp (or less,if its showing its age),you have your foot in it all the time trying to accellerate and keep up with traffic,and stog & go city driving sucks a lot more fuel down than if you could cruise steadily at 40-50 mph with it..my truck feels like it has tall gearing and the 265/75/16's also bog it down some too,the TH400 isn't the best for mpg either really..

I dont beleive the guys bragging about the 6.2's getting into the 20-25 mpg range,they must live on a downhill slope or have strong tail winds all the time or something..maybe the 1/2 ton 2wd ones with overdrive trannies might,but I doubt its consistent..

I just assume have a 250 straight six,it gets about the same mpg,starts in winter easily,and is a lot easier to work on,plus gas is 40+ cents cheaper a gallon since I started using my truck as my only road vehicle (figures,dont it?:rolleyes:)..
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My 1/2 ton C1500 GMC, 6.2 diesel, 700R-4, 3.42's and 235's pulls down consistent 25 mpg highway. I've only had it 6 1/2 years though...

Seriously, I filled up both tanks last summer, left Edmonton Alberta and drove to Surrey BC (780 miles) I didn't have to stop for fuel, and still had 3/8 of a tank and a touch under 1/8 tank when I got there. Total to fill in Surrey before leaving was 30.5 US gallons (115 liters). Total mileage was 25.57 mpg.

Not flat, no tailwind, not downhill all the way. Feel free to check google earth for a satellite view of the terrain. It's mountains all the way...

That is regular fuel mileage with that pick-up. In town it still surpasses 20 and that's real world observed fuel mileage on a truck with 280,000 km on it. (173,000 miles)
 
Avery4jc said:
I get about one hour per gallon on the rocks and when I used to take it to the dunes I'd burn about 15 gallons per day of fun!

Those are the only way to calculate MPG's in these trucks. :)
Click to expand...

Love this so much.
 
tRustyK5 said:
My 1/2 ton C1500 GMC, 6.2 diesel, 700R-4, 3.42's and 235's pulls down consistent 25 mpg highway. I've only had it 6 1/2 years though...

Seriously, I filled up both tanks last summer, left Edmonton Alberta and drove to Surrey BC (780 miles) I didn't have to stop for fuel, and still had 3/8 of a tank and a touch under 1/8 tank when I got there. Total to fill in Surrey before leaving was 30.5 US gallons (115 liters). Total mileage was 25.57 mpg.

Not flat, no tailwind, not downhill all the way. Feel free to check google earth for a satellite view of the terrain. It's mountains all the way...

That is regular fuel mileage with that pick-up. In town it still surpasses 20 and that's real world observed fuel mileage on a truck with 280,000 km on it. (173,000 miles)
Click to expand...


Well,thats great mileage for a truck with that high a mileage on it for sure..

If I tried checking google earth on this computer,it would take longer than your trip to Surrey did!..if it would download at all...:rolleyes:..I beleive you..


I did mention maybe some 2WD C-10's with overdrive could get 20+ mpg,I dont see any 4wd old GM diesels getting that kind of mileage around here
though...especially mine..I never had my K-10 Suburban registered yet,I dont know how that will be on fuel with 3.73's and small 15" tires,the 700R4 might help a lot on take offs and having overdrive (if it wasn't messed up that is--as it stands now it wont go into OD most of the time and will lose reverse when hot I was told when I got it)..I wouldn't expect more than 15 mpg out of that big barge,its probably heavier than my plow truck..has a 40 gallon tank too!..:eek1:

My truck has a lot against it as far as being a mpg champ,but I guess its still better than a gas V8 of any size would be--the TH400,whatever gearing it has is a factor--(someday I should pull the diff cover off and see what ratio it has,and change the fluid,which I doubt has ever been changed too!),I think it has 3.42's or even higher gears if they had anything in a 14 bolt SF like 3.23's or 3.08's...
It weighs 6200 empty,feels like it has a good amount of rolling resistance,and taking off from a dead stop seems to be a chore for it,especially if its uphill at all..since I put 265/75/16"s on it it is really doggy on take offs..it would be better off with smaller tires probably..

I also dont know if it has the diesel torque converter,the tranny isn't a 4wd case,its a car or 2wd case with the typical dust cover--no cast cover to bolt the thrust bars too,they are tied up out of the way..that could rob it of a few mpg for sure..and the areodynamics of a cinder block and the lund visor probably help none also!..:doah:

I wonder what a 6.2 would deliver for mpg if you put one in a lighter car like an old 68-77 Nova ..bet it would get 25+ mpg easily,and probably be pretty decent for performance as well...
 
just read this whole thing looking for "5.3 in square body" numbers..... NOT 1:rolleyes: is everyone thats done it ashamed to admit their numbers...:dunno: or better than us for having the combo:haha:...


them are the numbers i wanna see.

my burb in current state 350tbi/700r/208/3.73/33"s gets about 13-15 at 55-60 mph. goes down from there up
 
My 72 blazer on 35s with a 350 carburated about 8-10 mpg. My 94 blazer 350tbi on 32s gets 17-20 mpg. Not bad for 200,000 miles. Loved the smiles per gallon rating. Lol
 
i have a 76 with holley 650 double pump mechanical second 350/350/203 non converted (full time) with 3.73 gears 4" lift 35" tires speedo is off(was like that when i got it and not sure how to correct it) 30 gal tank. i have only put 3 tanks of gas in it since i have owned it, and im getting a consistant 7.28 all city. with the rod knocking at around 3000rpm i dont like to go fast for very long. and i havnt gone over 35 since the day i brought it home with the front spring bushings being shot and all shes a hand full.:D

even my 1994 ram 2500 5.2l auto trans all stock, would average 10 in the city. i used to get excited when i would get 12 out of mixed driving.

i also have to add that i only use 100% gasoline 100% of the time.

in my ram i could get about 400 miles out of a tank with 100% and only 275 or so with 10% ethinol

just a warning to everyone winter blend is coming in about two weeks we can all expect a 10%or so loss in mileage.
 
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