8 MPG?

[Arkansas_V8]

IIRC, it depended on what GVWR/brake system was ordered for 3/4 Ts. Could have been either SF or FF

Weren't the FF alot more common on older 3/4 tons? I found quite a few in early 70's 3/4 tons. My current one is from like a 73 I think.

 

[Wumbo]

IIRC, it depended on what GVWR/brake system was ordered for 3/4 Ts. Could have been either SF or FF

Possibly. I have the 8600# GVWR chassis.

Also, feeling pretty good about getting 12 mpg with my 454 after reading this thread.

 

[Vbb199]

Weren't the FF alot more common on older 3/4 tons? I found quite a few in early 70's 3/4 tons. My current one is from like a 73 I think.

My dad's 3/4 Ton 74 is a camper special, it's got a 14b ff rear end in it with some sort of sway bar on the ass.

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[86454k30]

For clarity...…….
73-80 C20, K20 and K30 got FF14bolt
81-87 C20 350 trucks and K20 got semi floater 14 bolt
81-87 C20 454 trucks, C30 SRW and cab chassis and K30 SRW and cab chassis got full floater 14 bolt

 

[Dmack]

Interesting. My 83 K20 has a 14ff. Assumed it was original, but not sure now.

 

[Paladin]

Just to point something out, when driving something down the road with basically the same aerodynamics as a cinder block, (and a really heavy cinder block at that,) you probably aren't going to get good gas mileage! Just sayin...

 

[80BrownK10]

Just to point something out, when driving something down the road with basically the same aerodynamics as a cinder block, (and a really heavy cinder block at that,) you probably aren't going to get good gas mileage! Just sayin...

Thats a great quote!!

 

[gotyourgoat]

Just to point something out, when driving something down the road with basically the same aerodynamics as a cinder block, (and a really heavy cinder block at that,) you probably aren't going to get good gas mileage! Just sayin...

Just a minute there professor...

Now I will give you that a 73-87 truck is like throwing a brick into the wind compared to today's plastic suppositories. However, it was engineered, tested and built to be more aerodynamic than the previous generation so many have a hard on for.

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[legopnuematic]

This is my Vacuum Gauge I have mounted to the column in my 76, got it at a swap meet for a few bucks.
My 76 C10 with 357 (0.040 over 350), just barely 9:1 static, Howards CL112561-12 cam, Summit 165cc iron heads (72cc,2.02,1.60), Edelbrock 2101 intake, Q-jet, and long tube headers into 18 inch glass packs, TH350 and 3.08 rear with 235/75/15's gets around 12. Mix of mostly city, but some highway. Does pretty good on the highway when you can keep it at a constant speed. Then it'll get 15 or so doing 70 or so. However it tends to drop now that I found it pulls hard to 5500rpm, which is fun to do nearly 60 in 1st...

I need to once I'm less busy do a comprehensive re tune and take a nice little trip and see what it'll really do

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[shiftpro]

This is my Vacuum Gauge I have mounted to the column in my 76, got it at a swap meet for a few bucks.
My 76 C10 with 357 (0.040 over 350), just barely 9:1 static, Howards CL112561-12 cam, Summit 165cc iron heads (72cc,2.02,1.60), Edelbrock 2101 intake, Q-jet, and long tube headers into 18 inch glass packs, TH350 and 3.08 rear with 235/75/15's gets around 12. Mix of mostly city, but some highway. Does pretty good on the highway when you can keep it at a constant speed. Then it'll get 15 or so doing 70 or so. However it tends to drop now that I found it pulls hard to 5500rpm, which is fun to do nearly 60 in 1st...

I need to once I'm less busy do a comprehensive re tune and take a nice little trip and see what it'll really do

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Do you know what the squish measurement is?

 

[dvdswan]

Do you know what the squish measurement is?

It really depends on the pressure and freshness of the grape.

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[shiftpro]

It really depends on the pressure and freshness of the grape.

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Haha...
So then you don't know what I'm talking about?
It's the most overlooked aspect of engine building. You will never make any power or fuel economy without compression and a tight squish zone... like
.035. If the squish zone is as wide as say, a grape, you will get horrible fuel economy and be gutless at the same time.

 

[RecklessWOT]

WHOA, 8MPG from a lifted 3/4 ton with 35s and most likely a 3 speed auto? By my calculations you should be getting at least 42mpg... in your mother in law's Prius...

Yeah man, that's about normal. While slightly on the low side (that sounds like big block territory), the fact that you're purely around town with little to no highway driving make it sound that much more normal. What are you running for exhaust? Do you like the way it sounds? Driving around town playing with that right pedal even slightly just because it makes cool sounds is more than enough to completely screw your gas mileage. Around town I'm lucky if I get 10mpg in my 1/2 ton burb with a friggin 700r4 and 3.73s riding on 33s...

My 4cyl Subaru that I DD only averages 19mpg (mostly highway, I get about 14 around town) because I enjoy making turbo sounds... It's reeeally easy to screw your gas mileage unless you're paying good attention to how you're driving specifically looking for fuel economy, ESPECIALLY in a 3/4 ton truck...

 

[82sbshortbed]

You don't drive these squares for gas mileage. When they started trying to squeeze as much gas mileage out of these trucks is when they started being less cool to me. That's why I bought a square and not an OBS truck. IDC about gas mileage because I'm fixin to drop in the BBC 454 sittin in the garage. I hope before Christmas or right after the New Year.

I'll be getting rid of the 305 I'm pulling out. You could come get it and get better gas mileage. Lol

 

[MisterB]

WHOA, 8MPG from a lifted 3/4 ton with 35s and most likely a 3 speed auto? By my calculations you should be getting at least 42mpg... in your mother in law's Prius...

Yeah man, that's about normal. While slightly on the low side (that sounds like big block territory), the fact that you're purely around town with little to no highway driving make it sound that much more normal. What are you running for exhaust? Do you like the way it sounds? Driving around town playing with that right pedal even slightly just because it makes cool sounds is more than enough to completely screw your gas mileage. Around town I'm lucky if I get 10mpg in my 1/2 ton burb with a friggin 700r4 and 3.73s riding on 33s...

My 4cyl Subaru that I DD only averages 19mpg (mostly highway, I get about 14 around town) because I enjoy making turbo sounds... It's reeeally easy to screw your gas mileage unless you're paying good attention to how you're driving specifically looking for fuel economy, ESPECIALLY in a 3/4 ton truck...

I've got headers and Flowmaster exhaust. Sounds great. I don't drive like a grandma, but I don't drive like a kid with Dad's Camaro either.

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