Am I crazy to expect more than 10 MPG

[80BrownK10]

With 4:10 gears, good luck on MPG.

I was thinking the same thing! I thought 10mpg with 4.10's was pretty good.

 

[Snoots]

If it starts easy, idles well, runs well and stops better . . . enjoy your ride!
For MPG, no jackrabbit starts, no passing gear; just have fun as is!

 

[Bextreme04]

You could always go for the LS swap if you want power and fuel efficiency. My 2011 Suburban with 5.3/6l80, 4.10's and 33's gets about 14mpg around town and up to 20mpg on the freeway at 70-75mph. My 1980 K25 with 350/TH400/NP205, 4.10's and 35's has seen 9mpg max.

 

[longbeach]

Grit dog, thanks. Great story

 

[AuroraGirl]

you are driving a very heavy rectangular box with modern fuels, a fresh engine, but an old timy setup nontheless, I think 10mpg is not unfair to ask but if you look to the mid 2000s HD 2500 chevys with a 6.0 and 4x4 werent all that far ahead on mpg compared. So the gains to be had may be pricy and require some dedication

 

[Jethro224]

My 79 K20, 350/465/205/4:10 on 35's always got about 9 mpg. No matter what. Even with a heavy trailer.
Haven't figgered mpg on my current square with similar setup but I bet it's pretty close.

 

[oldretiredafguy]

But think of all those panties you're dropping while driving your square. Lessens the pain at the pump.

 

[AuroraGirl]

But think of all those panties you're dropping while driving your square. Lessens the pain at the pump.

I mean if you want to go THAT far a warm hole is a warm hole.. who am I or you to judge, truly. It may not go far as a new car but 20 bucks is still gas.

I like your forward thinking attitude!

(LOL, Im joking!!!)

 

[longbeach]

Thanks to all. I guess 10 mpg is all I can expect. I do have a spare edelbrock which I did the jets and rods for one spot leaner on the tune graph. I'll give that a try when the weather warms...

 

[bucket]

Thanks to all. I guess 10 mpg is all I can expect. I do have a spare edelbrock which I did the jets and rods for one spot leaner on the tune graph. I'll give that a try when the weather warms...

You may find a slight increase in efficiency, just with warmer weather alone.

 

[longbeach]

fingers crossed

 

[LateOnTheBrakes]

I get about 16 mpg in my truck. But I am LS-swapped, 3.08 gears, and 33" tires.

 

[Rocky Veley]

I have a 1986 K20 with a crate engine with fewer than 5k miles. 350/TH400, 4:10 gears, Edelbrock 1406 carburetor. Truck runs fine, Starts fine. Stops fine. Carb is not that old and I tried a brand new one. All I get is 10 MPG, no matter what. New plugs, new wires. Timing is about 10 degrees BTDC. Any ideas?

That sounds low. My 98 c30 with 454 gets 10mpg. 85 chevy K10 with 6.5 turbo diesel gets 24 mpg . Depends on your driving habits too. 4;10 with no overdrive would not give you good mpg. Mind you the Canadian gallon is bit bigger. 4.5 liters compared to 3;78 liters in US gallon.

 

[Scribbles]

I have an 89 Suburban with all stock 350, 4x4 and 33 inch tires. My friend has the same exact tuck and tires with the only difference being he has a 454 engine.
I get 10 mpg and he gets 13. His reasoning is that the 454 doesn't have to work as hard to lug around all the weight with a small block.

 

[Bextreme04]

I have an 89 Suburban with all stock 350, 4x4 and 33 inch tires. My friend has the same exact tuck and tires with the only difference being he has a 454 engine.
I get 10 mpg and he gets 13. His reasoning is that the 454 doesn't have to work as hard to lug around all the weight with a small block.

Sounds more like his speedometer is off. I've only ever heard of a 454 getting that kind of mileage with fuel injection and overdrive.