gas mileage

[carolinajohndeere]

Hi: I just bought a 1972 C50 with a grain dump bed. The brake lines were shot along with some wheel cylinders. Just got all that fixed and started driving the truck. It has a 350 engine, a 4 spped trans., and a 2 speed rear end. The rear end is a 6.50 ratio in hi range.

Anyhow, the truck runs great. The only problem is that it is getting reall bad mileage, less the 5 mpg. I know this is a low geared rear end, but a 6.50 was in a lot of the Chevy trucks.

What has been you experience with gas mileage on one of these. Once I know what I should be getting, I will start digging into the fuel system if needed.
Thanks in advance for your help.

[South Florida C50]

It's never gonna be great, but you can make it better doing a few things that I did to my 1969. I had the same setup as you before I turned it in to a pickup. Try to keep up on the routine maintenance, new plugs, new wires, better air filter,change your distributor to an HEI, if your still using points. And the number 1 thing I did that really helped was upgrade to a high-flow exhaust system! It has to breath better to be more efficient. Night and day difference in the mileage.

[C10 - C90 Bill]

Great advice on the Exhaust.

It will sound a whole lot better too, lol.

Also as mentioned, give the engine a good "Super Tune".

I had both, a Flow-thru Exhaust and a Super Tune on a lot of my Chevys and I would get some great mileage out of them.

Also important is "how" you drive it.

[jumpsoffrock]

Once I swapped my rear gears from the 6.5:1 to the 4.86:1, I ended up driving it about 70 miles north to pick up a car. Topped off the gas in town, and as soon as I exited freeway again. Doing a rough calc, I got 10mpg. I was very satisfied with that.

I haven't even done a tune up on it! In 25 years! Still running the same plugs, wires, and points that have been sitting on it since my dad was given it in ~1989.

Tare weight is ~8400lbs., 327ci with 2bl rochester, 4-spd, 2-spd rear



P.S. I have new plugs etc, a junkard HEI, the need for a new exhaust, and finally changing to an electric cooling fan coming down the pipes though.

I really can't wait to see what mileage it gets after that.