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03-09-2010, 12:44 AM
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#1 |
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Registered User
Join Date: Jan 2010
Location: Oran, IA
Posts: 78
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K20 350 Q-jet MPG?
First off, I was on my way home with the '87 6.2 today, it started knocking badly and threw a rod.
I'm thinking of dropping a healthy 350 in it... for now at least. I have a 4 speed with 4.10 gears, the 6.2 could only pull off 13-14 MPG. I think I'd get about the same with a 350, especially with the quadrajet. Our '79 K20 350 Q jet Th400 4.10s could pull of 15-16 MPG on the highway  Not bad at all, IMOAny thoughts?
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'87 GMC K2500 Factory 6.2 Diesel, 4 speed. Converted to 350 (has cracked block) converting back to 6.2 '82 [COLOR="Sienna"]Cadillac Coupe Deville 350 DIESEL '93 Chev S10 2.8L 5 speed '98 GMC K1500 Z71 ext cab shortbox 6.5 DIESEL '96 Ford F250 7.3 Powerstroke |
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03-09-2010, 01:08 AM
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#2 |
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Registered User
Join Date: Feb 2007
Location: Austin, TX
Posts: 3,930
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Re: K20 350 Q-jet MPG?
I had a stock 350, turbo 350, 3.42 gears, and 28" tires that would do 14-15 on the highway. Only mods were an open element K&N filter, long tube headers, and true dual exhaust with turbo mufflers.
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1977 GMC Sierra Grande |
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03-09-2010, 08:52 AM
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#3 |
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Registered User
Join Date: Jan 2009
Location: Richmond, VA
Posts: 53
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Re: K20 350 Q-jet MPG?
My '85 C30 Dooley with 350/TH400, Q-jet, stock size tires and 4.10 gear gets 11 mpg highway. Much less around town. And I drive it very gently.
Last edited by Dooley Dude; 03-09-2010 at 08:53 AM. |
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03-09-2010, 09:54 AM
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#4 |
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One shot, one kill.
Join Date: Dec 2007
Location: Saratoga Springs NY
Posts: 859
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Re: K20 350 Q-jet MPG?
I have an 84 K20 with a 350 and a q-jet, and if I am REAL careful about how I drive I can get 17 MPG even with a 16 X 7 utility trailer behind it. Around town is a different story, it drops to about 10. I am running 3.08 gears and 31" tires.
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1984 K20 350M engine with 465,000 miles. Well, it's finally done!! Almost 2 years of work, but it was really worth the effort. Little stuff left to do is mount winch, wet sand & buff out and build belly pan\running boards. Body work takes lots and LOTS of beer!!!! God, Guts and Guns made America and God, Guts and Guns will preserve it! The worst thing you could do is get into my sights, but that don't matter, you'll never know it, cause you'll never hear the shot  Jim or Paladin whichever you choose.
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03-09-2010, 09:56 AM
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#5 | |
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Still plays with trucks
Join Date: Jul 2009
Location: Spokane, WA
Posts: 3,570
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Re: K20 350 Q-jet MPG?
Quote:
My K20 is a combination of a bit too much cam and way too much gear so I only get about 8 mpg in the city and 11 to 12 on the highway. With less gear (like your 4.10's) and a slightly smaller cam (mine is 280 degrees .485" lift cam I had sitting around so I used it instead of spending money on the right cam) you shouldn't have any problems getting 14 or 15 on the highway. Overdrive would help you a bunch on the highway.
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69 C10 shortbed stepside 400 small block - built like what a super sport truck could have been https://67-72chevytrucks.com/vboard/...d.php?t=484426 69 K20 lwb TBI 350 4L60E NP208 14-bolt Dana-44 w/disc 68 Camaro SS / RS 500hp 439 inch roller cam big block 4L80E |
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