My '79 gets 10 mpg. 350 with auto and 31 inch tires. I know, I know. Old trucks just get bad mileage and its the price you pay. But what is their I could do to improve the mileage? Plugs, wires, air filters, what?
well, like you mentioned these old trucks arent going to get good gas mileage to begin with but there are a few things you can do to help a little bit. for one thing, the biggest thing you can do if you're serious about getting better gas mileage is to get rid of those big ol' tires in favor of some others that are closer to stock size tires. also, make sure you air filter is a clean one. it does not have to be anything special but the main thing is that it is clean. also, make sure that you engine is running efficiently. your carb can make a huge difference in how much milage you get as well. are you running a race carb or more of a street application? then once you get the right carb on there you have to make sure that this is tuned correctly also. i'd say the biggest difference makers in MPG on these trucks are the tires you're running and the carb set up. i'm assuming yours is a 4x4 with those big tires so you cant really expect to get great as mileage to begin with but i'd start with these adjustments to begin with if you're serious about lowing your MPG.
I have a 79 K1500 4x4 but have a 4-speed manual transmision. I get between 14-16mpg (Canadian gallon - bigger) have stock 235/75R/15 tires and a stock 4bbl carb. I did have bigger tires on the truck at one time, but it wasn't worth the extra fuel it took to turn them. I recently had my carb cleaned out and adjusted my a mecahnic who knew his stuff. Just got home last night from a 5000km (3000 mile) road trip and was very happy with the performace and milage I got even considering that I was towing holiday trailer. I agree with OLD77 - loose the tires and you should see an immediate improvement. Steve
