MPG
- Thread starter shinkle
- Start date
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Memaloose
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- Dec 2, 2018
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- Location
- Dolan Springs, AZ
- First Name
- Tony
- Truck Year
- 1975
- Truck Model
- K20
- Engine Size
- 350
Lucky you!
My stock, all original 1975 350, 4 bbl, TH350, 4:10 differential, K20 gets about 14 mpg off road and 10-11 on highway. I only put about 1500 miles a year on it the past few years. It has 85,000 miles on it
My stock, all original 1975 350, 4 bbl, TH350, 4:10 differential, K20 gets about 14 mpg off road and 10-11 on highway. I only put about 1500 miles a year on it the past few years. It has 85,000 miles on it
Bextreme04
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- Oregon
- First Name
- Eric
- Truck Year
- 1980
- Truck Model
- K25
- Engine Size
- 350-4bbl
Man, I need to get my fuel injection and overdrive in... last time I checked my 350/TH400/NP205 equipped K25, she was getting about 7-9mpg. Supposedly the L29/4L80e combo should get me about double the power and jump the mpg up to 10-14mpg
SirRobyn0
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- First Name
- Rob
- Truck Year
- 1984
- Truck Model
- C20
- Engine Size
- 305
@shinkle I image your 350 is TBI? What you running for tranny and gears I'm guessing 700R4?
So my 1984 C20 305 - 700R4 - 3.41 rear gears will do mid 16 on the highway if I'm conservative... Keeping it around 60 - 65 mph my best is 16.9. However my back and forth from the shop is typically around 11MPG. I think you'll see there is some variation depending on setup.
So my 1984 C20 305 - 700R4 - 3.41 rear gears will do mid 16 on the highway if I'm conservative... Keeping it around 60 - 65 mph my best is 16.9. However my back and forth from the shop is typically around 11MPG. I think you'll see there is some variation depending on setup.
SirRobyn0
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- Rob
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- 1984
- Truck Model
- C20
- Engine Size
- 305
I did the exact same thing. I thought about going dual exhaust, but my truck has a dump kit on the factory box, and the hydraulic pump is on the inside of the frame on the passenger side. I could probably fit a muffler in there with a heat shield, but instead I did a high flow cat and IIRC 3" mid-pipe.
potent rodent
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- butch
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- 86 and 78
- Truck Model
- 1500
- Engine Size
- 350 and 305
thats good for a square body im getting 13.5 but thats with a rochester 2gc brl
Customblue
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- Brandon
- Truck Year
- 1986
- Truck Model
- K10
- Engine Size
- 489
I'm getting around 6 mpg with my 489. I built it to come alive 2500 -6500 rpm, and that's where she stays 90% of the time. I base it off how many smiles per gallon not miles per gallon though!
SirRobyn0
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- 1984
- Truck Model
- C20
- Engine Size
- 305
Yes it is, but while I can achieve 16, on a highway trip, no load, driving 60 and being conservative with the skinny petal, but in reality I don't get that kind of mileage. Driving faster or hitting the skinny pedal to much. The speed limit is 70 on the highways around here and time is valuable to. So at 70 to 75 it's more like 14 mpg. When I'm running around local its 11 to 10 depending on how much idle time.
