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Gas Mileage

Discussion in 'Chevy Trucks' started by 78K20, Jan 22, 2004.

  1. 78K20

    78K20 Member
    from WV
    Messages: 49

    I just got my truck back on the road and I was wondering if any avg of 10 to 11.5 mpg was good average for highway driving and if 7 to 8 mpg would be a normal average for the city. My truck is a 78' chevy 3/4 ton 4-wheel drive. It has a 350 bored .60 over 9 to 1 compression with headers, a corvette intake and 2 1/4 inch duals. The tranny is a TH400. The NP203 case has been converted to part time. The axle has 4.10 gears and I am running 285 75 16 mud tires. Is there anything I could do to improve mileage. I was thinking about a 700r4 but I heard it wasn't as bulletproof as the 400 and wouldn't hold up to plowing as good. Thanks for the help:)
  2. ratlover

    ratlover PlowSite.com Addict
    from IL
    Messages: 1,325

    nothing will improve gas milage enough to pay for itself anytime soon. With that an OD trany would help but you will have other mods to make especially depending on what trans you go with that will jack up the price even more.

    regearing would help but not that much and you will lose some acceleration. Remember you would have to change the front and the rears.....You may be able to swap axels fairly cheaply.....3/4 ton stuff in the 410 flavor are pretty desirable.....you might be able to trade even up with someone or get a bit of $$$ plus the axels.

    A general tune up might help but it sounds about right actually. The part time conversion is a help(I hope you just didnt put hubs in it and put the case into loc?) The 203 has a oil pump that dosnt pump in loc and some kits dont keep it going. A lite foot is the biggest help........

    Sounds like you have a nice desirable truck and you might be able to sell it for something else like a FI truck with OD that will do a bit better. Otherwise you are pretty much screwed since anything to substantialy increase milage wont really be cost effective IMO unless you drive it a long time.
  3. nachoschevs

    nachoschevs Member
    Messages: 58

    I would think that putting a smaller motor in it, or maybe one that is not so built up would do a little better, but who would want to do that.:D I think if you could get a set of 373 rears it may make your fuel mileage a bit better. I don’t think there is much that you can do to get better mileage out of an old Chev. Only thing you can do is just keep feeding the fuel to it and be glad you live in the US and your gas is not $4.40 a gallon like other countries. Nothing beats an old Chevy, so I would not give it up for a newer one (unless you want to sell it to me);) Just my 2 Cents though.