Improving Mpg 1979 K10

[BANova73]

What would be a good gear ratio to run in my 79 k10 with 33s and 4speed to optimize gas milage, i was also thinking about swaping out the 350 to a 454 for more power,would that help my mpg? id like to get around 14+ on the high way

[VileZambonie]

4 speed what? You need to specify a little more detail on your setup.

[Irish_Alley]

and what you want to do. mud? race? cruise?

[BANova73]

The trucks got a 350 4 speed running stock gears 1st 6.55. 2nd, 3.58, 3rd 1.70 and 4th 1.00. diff is 3.73, i currently have 33s with 16inch rims

[bake74]

     You have a SM465 transmission.  Typically know as a 3 speed with granny gear.  If you put a 454 in and can stay out of the gas pedal, you will not have to work it so hard.  We do have members on here that say they get better gas mileage from a properly tuned 454 than others with a 350.
     There is also the consideration of a overdrive transmission swap.  That will net you some mpg, though a lot of people do not believe the trade off ( cost vrs mpg ) is worth it.
     Running 33" tires and your 3.73:1 gear ratio is going to be your best bet for that setup.
     One last thing to consider, you did not tell us what transfer case you have.  205 + 208 are ok, but if by chance you have the np203 ( unlikely ), if it is still full time that will suck your gas mileage down in a heartbeat.  Most times they were converted to part time and they added front locking hubs, if you do not have manual front locking hubs, I would take a close look at your transfer case.

[Captkaos]

I don't think you will see 14's with a 454 in a 4x4...

[Irish_Alley]

with 4.10s if you get an od trans you will basically turn your 4.10s to 3.15s. so imo thats a good way to save money at the pump. but the swap will be up there and if you want to build the trans up that will hurt even more. you can pick up a 700r4 i think for 600-900 but then you have to get a new front shaft and get your rear cut down unless it comes with drive shafts

[rich weyand]

Some things you can do for mpg:
1) keep the heat riser on the air cleaner, or replace it if it is gone, so you get warm air into the carb when it's cold out.
2) keep pipe on the air cleaner snorkel to the radiator bulkhead, or replace it if it is gone, so you get cool air into the carb when it is hot out.
3) use synthetic engine oil.  I use Mobil1 10W30 with one little jar of ZDPPPlus per oil change.
4) use synthetic P/S fluid.
5) use synthetic gear lube in the tranny.
6) tune the carb with an A/FR meter to make sure you are not running richer than you need to.
7) install an electric fan to replace the mechanical fan.  You get rid of running that mechanical fan all the time, and you will more often run the engine in the temperature operating range where it is most efficient.  Our trucks have so much cooling capacity, the darn things always run cold, and that robs mpg.