Highway mileage-390?
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Highway mileage-390?
My '70 F100 Custom recently got ten mpg on a trip, but the carb is needing rebuilt. Back when I had a 2bbl Motocraft on it, 15 to 18mpg was the norm for my truck on the highway. It all depends on the tune of the engine. My '70 has a 390, 4bbl Holley, C6, 3.50 gears, 31x10.50x15's.
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Highway mileage-390?
4.10 gears, 255/70r16 tires. need I say more. I installed a 90 gallon gas tank in the bed. Now I don't stop as often. It just hurts when I stop.
I suspect 7-10 MPG is about what I see. But my engine is spinning at bout 3400 RPM on the highway. This may be where 7-11 got the term "Big Gulp" :-)
I suspect 7-10 MPG is about what I see. But my engine is spinning at bout 3400 RPM on the highway. This may be where 7-11 got the term "Big Gulp" :-)
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Highway mileage-390?
I forgot to mention my engine spins roughly 2500rpm @ 55mph. My engine has dual exhaust, but with the factory manifolds. You've got the right gears for decent mileage.The secret is tuning. Play with timing, fuel mixture, tire pressure, and everything else that may affect mileage. I tune for a few hours, and drive for a few days. Then I tune for a few more hours. Drive a few more days.
I have two timing lights, but neither of them get near my truck. I time by ear and seat of the pants. I use a vacuum guage to adjust my idle mixture. Don't forget to try different jets in your carb, too.
Good luck!
I have two timing lights, but neither of them get near my truck. I time by ear and seat of the pants. I use a vacuum guage to adjust my idle mixture. Don't forget to try different jets in your carb, too.
Good luck!
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Highway mileage-390?
Thanks for all the info!
I was just wondering if you guys have any tips on tuning the carb for better economy, and if could retard or advance my timing for better economy? It is set at 6 degrees BTDC right now (I think).
I need to get this thing to about 12mpg or more. I don't want to have to get rid of it..I love this truck, and it runs so good!!!
I was just wondering if you guys have any tips on tuning the carb for better economy, and if could retard or advance my timing for better economy? It is set at 6 degrees BTDC right now (I think).
I need to get this thing to about 12mpg or more. I don't want to have to get rid of it..I love this truck, and it runs so good!!!
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Highway mileage-390?
You said 390, but I thought you might want to know how a 360 (very similar) does. Mine spins about 2400 rpm going down the highway at 55 mph. Here are the mileage numbers in various road conditions: Highway: 10 mpg. In town: 10 mpg. Summer: 10 mpg. Winter: 10 mpg. Extra heavy on the gas, doing burnouts at every stoplight and such: 10 mpg. Driving for mileage: 10 mpg. See a trend forming? heh.
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Highway mileage-390?
Originally posted by rusty70f100
Sad part is, its true!
Sad part is, its true!
Scotty