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Gas Mileage

A

AZTBlazer

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Mar 30, 2000
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Glendale, AZ
I was just curious as to what everyone gets gas mileage-wise, and what mods do you have done to your truck. Just a late night thought. My 71 K10 gets between 7 and 8 miles a gallon, of course its got 180k on the original engine.
Tom
 
What do you have in it to get 7 or 8 mpg
I have 88Jimmy with Vortec 350 TPI 3.73 gears 31x10.5 tires
and get 13 1/2mpg 8 to 9mpg towing a 5500lb trailer
6mpg if there is a lot of hills

Soon to be 14bolt rear 4.56 Dana 60 4.56 Like need week!
35x12.5x16.5 BFG A/T
 
i put a jacobs omni magnum ignition in my 85 k5 with a new 350 and my gas milage went from 11-13mpg to 13-15 mpg plus 10-15hp. also a free flow exhaust and headers should help bring up both power and gas milage.
 
7-8 does seem kinda low. My set up is an 89 Jimmy, 350tbi, 700r4, 3.73 gears, 33" tires, jacobs coil & plug wires, hooker cat back. With good plugs I'm 14.8 mpg. My face is red on this one but I gotta tell you. I noticed a 2 mpg decrease and and later realized(after a couple weeks) that I hadn't unlocked my hubs the last time I wheeled

So Much to do, So LITTLE cash.
 
I just checked it after a whole tank full. I know I'm getting o.k. highway mileage because I made 2 100 mile round trips (total of 200 miles) on the first half of the tank (yes, filled to the filler tube), but didn't seem to get that great on the 2nd half of the tank (all city driving mind you, about 120 miles).

Total mileage was between 11 and 12 mpg. I'm going to check it again at the halfway point and only city mileage and I'll update this then...I guess if you can get 450 miles out of a tank you're doing o.k. so that's my goal.

88K5, 350tbi, 700R4, stock gears (?), 30x9.5x15's, 108000 miles on stock engine. PO did valve-job 15k miles ago. Time to change the plugs (after the next mileage check)

<font color=red>Steve88</font color=red>
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88K5 Silverado
[email protected]
 
I average about 10 mpg, that's not including my odometer is 8% slow. I'm actually getting a little better mileage. I have 35" MT's, 4.88:1 gears, TH350, and a full time NP203. It's carbureted but I do have a fresh, near stock 350 in it. I hope to improve mileage a bit when I put my NP205 in it. I think 7-8mpg is about right for an engine with 180,000 miles on it.
CB
 
Drove my Blazer to AZ. From Menifee CA. to Blyth CA. I got 10.5 miles to the gallon and from Blyth to Mesa AZ I got 8.6 mile to the gallon that is pulling a Pick UP Bed Trailor with a 350,350,203 w/part time kit,4" lift,4:56 and 35x12.5x15. Motor rebuilt 2 years ago but low miles on it, trany and transfer just re-built

C'moe

<font color=black>the blazer is "Back in Black"
 
Still getting better than 16 mpg on the hiway. Delorme maps says from here to folks place is 243 miles. I got 31 gal tank and I can pull up to the folks driveway with exactly 1/2 tank showing.
Ole Gal is completely stock right down to the aircleaner. 305 with quadrajet 4bbl.Automatic. 31.10.50's Goodyear Wranglers(changing to BFG's next month when lottery check gets here.)

<font color=green>Eagle86K5
smile.gif


<font color=red>Only guy I know that can get out of line in a one car funeral
 
I have a 1990 w/ TBI 350,700r4, 35" tires and 4.56 gears and still get about 15-16mpg with 156,000 miles on the odometer. Neither the motor nor the trans has every been touched. I do have dual flowmaster exhaust though...that may help in the gas milage.
 
my speedo has been broken for months, but I drive 20 miles round trip every day in town and every 5 days I put in 10 gallons. in my book that comes out to 10 mpg.
'77 K5

<font color=red>mudfanatic</font color=red>
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'89, 33's, mild exhaust, bad cat
14-15mpg, with speedo corrected for larger tire size
commute 25 miles each way to work, over hills, with strong head winds.
i hate being passed, but with gas @ $2.00........................

<font color=purple>delta9blazer</font color=purple>
 
'74 bone stock 350/TH350 (brand new GM crate engine last year though ;-) and '75+ hot-air choke intake manifold/Q-jet. 3.73 gear ratio.

I get 10MPG going up, down, sideways, at 35MPH 'round town or 80MPH on the highway to work. Doesn't seem to matter what I do.

Yeah, at two bucks a gallon gas ain't cheap, but maintenance costs (what maintenance? replace it when it falls off!) and parts costs are so low it's still cheaper than a new vehicle -- and damn more fun! ;-)

-- A

'74 K5 Blazer "Tank Grrl"
'77 Chalet sans Blazer
and more to come...
 
88 Burb with stock 350/700R4/NP208C,and Flowmasters with no converters,4:56's and running 38's! I get around 7 to 8 no matter if I am on the road or in town and I would guess she weighs 7000 lbs.
DirtyBurb.JPG
<font color=red> MO GAS LOTS MO

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<font color=red>BigBurb
tongue.gif

<font color=purple>IF YOU'RE SCARED, SAY YOU'RE SCARED !!
 
10MPG/8MPG remained even after installing a new Edelbrock Q-jet. My setup is 350/350/FTNP203/3.08/31"

I guess my one liner is appropriate in this thread:

<font color=black>//////
What the heck!...Drive it like gas is $0.50/gal!!!</font color=black>
cool.gif
 
OK. Here's an update. After the last fill-up I've managed to get about 70 miles before the fuel gage got the the full mark. Yes I filled it to pretty much the top of the tube, but at only 11mpg that would mean I either have one of the following two problems:

(a) I've got over 6 gallons of gas in the filler tube (ha-hardly!)
(b) I've got a bad fuel gage sending unit?

Do any of you see the same thing happen when you fill er up to the top? How many miles have you gone when it finally hits the full mark on the gage? (BTW: Takes about 28 gallons to fill it when it's been on empty for a day or so...hey I'm a daring guy!)

<font color=red>Steve88</font color=red>
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88K5 Silverado
[email protected]
 
Mine takes about 50 miles before it hits the full mark. I had a Pontiac 6000 that would go about 100 miles before the needle even moved at all! My dad's Toyota Camry is right on every time, including having exactly 4 gallons left when the low light comes on. GM engineering...

BTW, No offense to any GM engineers out there, I may become one when I finish school.

Joe
88 Jimmy
 
I get about 12 mpg all the time. I've got a 350/700/208 and added a K&N filter and a Jacobs ignition system with 33's. I haven't corrected the speedo so my torque converter rarely locks up anymore, that's soon to be corrected. Hopefully that should help out a bit. When it does lock up it's REALLY nice, 60 mph while barely touching the pedal is a great thing.

Joe
88 Jimmy
 
I get between 12-14 mpg on the stock '87 350 MT in the city. Highway is at a steady 15 mpg. Looking to put in some AC Delco rapidfire plugs next weekend and see if they really do save gas. I've got the 31 gallon tank. In response to the needle past "full" on the guage, seems like all GM cars/trucks do this. My K5 does this too. My brother's '96 Chevy Truck does the same. Also, two other GM cars I drive on regular basis do this as well. It's normal for GM.
 
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