What MPG should I get? how to improve?? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

alex19 · 11-29-2006, 12:23 AM

I'm new here and I recently bought a 78 GMC K1500 pickup with a 4brl. carbureted 350 and full time 4wd. It has stock-size tires and I get about 11 mpg...Is this normal? How can I get better gas mileage? The engine seems to be tuned fairly well and not run too rich/lean. I've heard the tornado things and magnetic fuel clamps really don't work.

How hard would it be to convert to a TBI system? Cost? I really would like the better runnability of FI as well. Anyone done this?

I know a tonneau cover helps with gas mileage and I'm already going to do that...any other easy ones?

Thanks in advance for any help! -Alex

87 STEPPER · 11-29-2006, 06:50 AM

Alex,

I think thats about normal for your truck!

Why is it full time 4wd?

If you could run in 2wd most of the time and go to 4by when you need it you could probably pick up a few mpg's there.

As far as converting to TBI it's not that hard to do but it's costly maybe 2 grand.

Theres several conversion kits on the market to do this Holley,& Edelbrock and there are some others.

An affordable way to go would be a junk yard vehicle like a later model full size truck or van you could strip all the TBI system out and transplant it into your truck for maybe 7 or 8 hundred dollars.

Good luck.

mhicks · 11-29-2006, 02:17 PM

I have a pretty new (2000 miles) GM crate 350 260 horse 350 ft lbs torque witha 700R4 and I am only getting 11-12 mpg. It has a new high performance GM electronic ignition and a new Edlebrock 600CFM carb. I would sure think it should get better than that but it don't.

SSC's76 · 11-29-2006, 02:46 PM

Manual locking hubs are good for at least 1 MPG better. Thats a $70 investment that will pay for it's self in a short time. Other then that I wouldent expect too much more without some major fine tunning. I know several people running Holley and Edelbrock TBI and MPFI systems none of which do better then 14 MPG on mildy built engines most get around 11-12 MPG real world figures.

A quick glance over at fueleconmy.gov will also show that the 5.7 4wd isnt rated much more then 11-14 city with a whopping 16 highway. I beleive those MPG ratings were taken at 55 MPH too.

No, none of that add on junk works either.

11-29-2006, 12:23 AM	#1
alex19 Registered User Join Date: Nov 2006 Location: Spokane Posts: 3	What MPG should I get? how to improve?? I'm new here and I recently bought a 78 GMC K1500 pickup with a 4brl. carbureted 350 and full time 4wd. It has stock-size tires and I get about 11 mpg...Is this normal? How can I get better gas mileage? The engine seems to be tuned fairly well and not run too rich/lean. I've heard the tornado things and magnetic fuel clamps really don't work. How hard would it be to convert to a TBI system? Cost? I really would like the better runnability of FI as well. Anyone done this? I know a tonneau cover helps with gas mileage and I'm already going to do that...any other easy ones? Thanks in advance for any help! -Alex

11-29-2006, 06:50 AM	#2
87 STEPPER STILL PLAYS WITH TRUX Join Date: Nov 2002 Location: Melbourne, Fla. Posts: 2,764	Re: What MPG should I get? how to improve?? Alex, I think thats about normal for your truck! Why is it full time 4wd? If you could run in 2wd most of the time and go to 4by when you need it you could probably pick up a few mpg's there. As far as converting to TBI it's not that hard to do but it's costly maybe 2 grand. Theres several conversion kits on the market to do this Holley,& Edelbrock and there are some others. An affordable way to go would be a junk yard vehicle like a later model full size truck or van you could strip all the TBI system out and transplant it into your truck for maybe 7 or 8 hundred dollars. Good luck. __________________ ~~Bruce~~ MY 87 STEPPER MY 99 2D/WD TAHOE

11-29-2006, 02:17 PM	#3
mhicks Registered User Join Date: Jan 2004 Location: Weatherford,Tx Posts: 747	Re: What MPG should I get? how to improve?? I have a pretty new (2000 miles) GM crate 350 260 horse 350 ft lbs torque witha 700R4 and I am only getting 11-12 mpg. It has a new high performance GM electronic ignition and a new Edlebrock 600CFM carb. I would sure think it should get better than that but it don't.

11-29-2006, 02:46 PM	#4
SSC's76 No No Join Date: Jun 2005 Location: Pueblo Colorado Posts: 1,781	Re: What MPG should I get? how to improve?? Manual locking hubs are good for at least 1 MPG better. Thats a $70 investment that will pay for it's self in a short time. Other then that I wouldent expect too much more without some major fine tunning. I know several people running Holley and Edelbrock TBI and MPFI systems none of which do better then 14 MPG on mildy built engines most get around 11-12 MPG real world figures. A quick glance over at fueleconmy.gov will also show that the 5.7 4wd isnt rated much more then 11-14 city with a whopping 16 highway. I beleive those MPG ratings were taken at 55 MPH too. No, none of that add on junk works either. __________________ 1976 Custom Deluxe SWB Med FMB.3/4 Drop. Gen VI 454, Muncie HD 3 speed With Modified OE Hurst Shifter, 3.73 12 bolt, GMPP HO roller cam, Hooker headers, Performer intake with modified Q-jet, Accel distributor. Best 1/4 12.3 @108. Funnest run 19.84 @88 full 1/4 mile burn out. 1997 K1500 ext cab 5.7 stock except muffler Last edited by SSC's76; 11-29-2006 at 02:55 PM. Reason: casue I can Muhhhha



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