Engine /trans suggestions

[carteaco]

I've got a 66 Chevy 3/4 ton 350/TH400 & 4.10 gears. It gets less than 10 MPG. Any suggestions for a reasonable engine/trans swap or other mods to get better MPG.

[Daytona100]

I've got a 66 Chevy 3/4 ton 350/TH400 & 4.10 gears. It gets less than 10 MPG. Any suggestions for a reasonable engine/trans swap or other mods to get better MPG.
Check out a gear venders unit and maybe change the rear gear ratio to a 3.73.

[curtis73]

I might suggest an LT1 swap. Its an easy swap since the bellhousing pattern, engine mounts, and dimensions are the same, but it adds EFI and far superior heads. It also has reverse cooling which sends the coolest water to the heads which is great for towing.
For not much more than a standard rebuild you could upgrade to a 383. At that point I recommed the Comp 304 cam which is a torque monster. Many of us Impala SS guys use that cam and its hard to keep the rubber from melting. Pair it with some 3.73s, an overdrive (like a built 700r4) and you'll be in heaven.
If you want the ultimate in torque and very respectable mileage, consider a Caddy 500. They make diesel torque and only weigh a few more pounds than a small block chevy. Motor mounts are available aftermarket and the 4.3 x 4.3 bore and stroke makes massive cube potential. 529 is pretty easy with some machine work to the crank. I have one in a 66 Bonneville and its making 390 hp and 550 tq. I get 18 mpg empty with 3.42s and a .78 OD.
If you're up to the minimal fabriction required for the caddy, you won't be disappointed. If you just want to bolt something in and tune the EFI, do an LT1

[LHC30Victory]

Put in a 383 stroker to get the torque, use EFI for fuel management, leave the gears alone and put 35's on it....
I had built an 85 K5 Blazer 4X4 with a 383, 700R4 trans, 373 gears and 33 tires. Driving from LHC to Upland it got about 25mpg at 75mph..... Lots o' torque off roading and pulling my 30' Victory up and down the hills at the lake.