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#1 |
Formerly yellow72custom
Join Date: May 2001
Location: Austin, TX
Posts: 7,531
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Re: mileage motors
3.08 was standard on most trucks in the 80's, and I've heard of even 2.73's....with a 700R4. One of my friends had an '86 K10 with a 305/700R4/3.08 combo. With 32" tires it practically idled down the freeway, but got maybe 10-11 mpg going 75, and had no power, with its worn out, improperly tuned 305.
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'72 Chevy C10 Mild 350/TH350/3.07. Ochre/White. Old high school ride. '70 GMC C2500 '62 327 4bbl/SM465/4.56-geared Dana 60. White/White. Project or parts truck. '97 Saturn SL DD. 1.9/5-speed. 40+ highway mpg |
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#2 |
I have a radical idea!
Join Date: Jan 2005
Location: Sweet Home Alabama!
Posts: 6,513
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Re: mileage motors
I would recommend one of the smaller Comp Xtreme 4X4 cams. They produce great low end torque, and helps the push the truck down road better, The problem with a small cube engine sometimes that that you have to give it lot of throttle to make them feel like thay have any power negating the fuel mileage advantage of having a smaller engine. If you can do it, get the CR up to 9 - 9.5:1 and go with a cam designed for low end power. As Pynotechnic said, I would get a freshly rebuilt Q-jet if you can't go with EFI. 18 - 20 MPG on the highway should be no problem with a high geared rearend.
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'67 C-30 Dually Pickup 6.2 Turbo Diesel, NP435 ‘72 C-10 SWB , 350 4bbl, TH350 '69 C-10 SWB , 250 L6, 3 OTT '69 GMC C3500, dump truck, 351 V6, NP435 '84 M1009 CUCV Military Blazer 67 C-30 Turbodiesel build thread http://67-72chevytrucks.com/vboard/s...d.php?t=254096 My trucks http://s226.photobucket.com/albums/d...ediafilter=all Member of the 1-Ton Club! |
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#3 |
Who's got steelies?
![]() Join Date: Feb 2006
Location: Morrison, Oklahoma
Posts: 1,026
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Re: mileage motors
My 305 has 189,000 miles on it.
It came from a '77 Monte Carlo. It was repeatedly overheated on a trip from OK to Calif. & back. Has only a 2bbl carb Sat for a year before being put in the truck. Best milage (after tuning it up a few weeks ago) was 18.6 mpg for 1 tank. Before it was 15.mpg. In the Monte, best was on a trip from OK to NM was 21mpg. I am running 3.73 rear gears, stay about 60 on the highway. Future plans: 4bbl Q-Jet or Edelbrock, 3.08 gears.
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![]() ![]() ![]() ![]() ![]() ![]() How to add a trip odometer to your 67-72 stock speedometer How to rebuild your Q-Jet My Truck Page My Youtube Channel |
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