Best combination for fuel mileage

[jaspencer]

I have a 1978 k10 with 350v8/auto trans/NP203/full time 4x4/32"tires. I've had this truck for 18 years and at one time drove it every day. I now use an XJ to and from work.  I would like to again make it my daily driver but would like to be able to  get at least 16 mpg out of it. I have a 1 ton 1991 for work so I'm willing to go with a smaller engine and lose power, but I'd at least like to stay with the 32" tires for some of the hunting trails I go on. Any suggestions.

[VileZambonie]

Convert from full time and install EFI

[eventhorizon66]

Make the truck a weekend play thing and buy a used Honda civic.

[Lt.Del]

losing cubic inches and horsepower wont necessarily get you increased mpg.   Some 454's get better mpg than my 350's.

My 91 2500 suburban 5.7 4x4 with tire size 33 gets around 17mpg on the interstate and 12-15 in city. It is TBI.  I think that is very reasonable for a sub. 

Vile said something very important though, get rid of the carb and convert to fuel injection.  A bit of a chore with new tank, lines, pump, etc..depends on how bad you want to increase mpg.

If you do a lot of highway driving, you may want at least a 3.50 diff. ratio.  You didnt mention what your gears are.  If you do a lot of city driving, I'd have probably 4.11's on it with 32 inch tires.   

Remember, if it is underpowered, you can use more gas by keeping the accelerator down all the time to go anywhere.

[jaspencer]

Thanks guys, It's just always been my favorite vehicle and I've found myself not driving it much because of the gas mileage. I'm not sure of the gear ratio, but I know it came from the factory with positive traction and I used to pull a four horse gooseneck trailer loaded and had no problem until it came time to stop and the trailer brakes weren't working. (Long story..no injuries though).  I'm leaning towards a diesel engine and running veggy oil.