Normal MPG from 400 SBC

[Eddie H.]

My 69 with a sb 400, Edlebrock carb, 3:08 gears, and 255 70 15 tires gets around 11-14 highway mpg depending on how heavy my foot is. I think I got 15 one time, going down hill with a strong tailwind.

[Jtrux]

Originally Posted by special-K

My Highlander gots 10 or a bit better.It`s got a 400,4spd,4.10s,35" tires and I let the torque drive the truck.The only time the revs get up there is hiway driving.But,at 65 it`s just rolling down the road effortlessly,even though the revs are at around 3,500 or so.
This truck gets noticably better milage than my Sierra with 350,TH350,and 33" tires.

Wow!! 3500?? Really?? I was planning on running the same gears with 35's on my blazer but didn't realize how high the rpm's would be, right now at 65 it does about 2400 with 3.08's. Maybe i'll reconsider cuz I really like the way it cruises on the highway right now.

[Greubin]

Just for reference, I'm getting 16mpg @ 70mph / 2200rpm's commuting 30mi on Friday's in smooth traffic ( no stop n go ).

My setup @ sea level

350ci 290hp crate engine
Eddy performer manifold
Eddy 1406 carb, rejetted and tuned for best lean performance.
Summer HEI distributor, stock coil
700R4 w/ 4.10 rear and stock 16.5 wheels / tires
Vacuum is 10-11" at 2200rpm cruising

I was toying with the idea of getting a CDI unit, hoping that it would improve gas mileage...anyone know for sure?

[WyoCustomC10]

Just my 2 cents, I have almost the same setup as you, except I have 3.73 gears. You might want to get that sucker rejetted (if you have not already) for 5,000 ft if you live in CO. It will run better and burn a lot less fuel. I would also suggest a different gear set. I get around 12 mpg running between 4,000 ft and 6,000 ft above sea level. With the Carb you have, make sure you get different squirters if you rejet it, or it will stall on take off.

Sweet looking ride by the way!